| United States |
|
|
|
string_char_traits
Standard C++ LibraryNAME
string_char_traits_ - A traits class providing types and operations to the basic_string container.
SYNOPSIS
#include <string>
template <class charT> struct string_char_traits struct string_char_traits<char>; . struct string_char_traits<wchar_t>;
DESCRIPTION
The string_char_traits struct provides elementary operations to instantiations of basic_string. As with all traits classes, string_char_traits is used to specialize the behavior of a template. In this case, the traits class provides functions based on character type to the basic_string template.
Specializations of string_char_traits are provided for char and wchar_t. These are used to define, respectively, string and wstring.
INTERFACE
template <class charT> struct string_char_traits .
{ typedef charT char_type; static void assign (char_type&, const char_type&); . static char_type* assign (char_type*, size_t, const char_type&);
static bool eq (const char_type&, const char_type&); . static bool ne (const char_type&, const char_type&); . static bool lt (const char_type&, const char_type&); . static char_type eos (); . static int compare (const char_type*, const char_type*, size_t); static size_t length (const char_type * s); . static char_type* copy (char_type*, const char_type*, size_t); static char_type* move (char_type*, const char_type*, size_t); static const char_type* . find (const char_type*, int, const char_type&); };
TYPE
char_type The basic character type. Same as the template parameter.
OPERATIONS
static void assign (char_type& c1, const char_type& c2) Assign one character value to another. The value of c2 is assigned to c1.
static char_type* assign (char_type* s, size_t n, const char_type& a) Assign one character value to n elements of a character array. The value of a is assigned to n elements of s.
static bool eq (const char_type& c1, const char_type& c2) Return true if c1 equals c2.
static bool ne (const char_type& c1, const char_type& c2) Return true if c1 does not equal c2.
static bool lt (const char_type& c1, const char_type& c2) Return true if c1 is less than c2.
static char_type eos () Return the end of string value for the the character type. Typically char_type().
static int compare (const char_type* s1, const char_type* s2, size_t n) Compare n values from s1 with n values from s2. Return 1 if s1 is greater than s2, -1 if s1 is less than s2, or 0 if they are equal.
static size_t length (const char_type * s) Return the length of the null terminated character array s. The eos terminator is not counted.
static char_type* copy (char_type* s1, const char_type* s2, size_t n) Copy n values from s1 to s2. The ranges of (s1,s1+n) and (s2,s2+n) may not overlap.
static char_type* move (char_type* s1, const char_type* s2, size_t n) Move n values from s1 to s2. The ranges of (s1,s1+n) and (s2,s2+n) may overlap.
static const char_type* find (const char_type* s, int n, const char_type& a) Look for the value of a in s. Only n elements of s are examined. Returns a pointer to the matched element if one is found. Otherwise returns s + n.
SEE ALSO
basic_string, traits
STANDARDS CONFORMANCE ANSI X3J16/ISO WG21 Joint C++ Committee
basic_string
Standard C++ Library Copyright 1996, Rogue Wave Software, Inc.NAME
basic_string,string - A templated class for handling sequences of character-like entities. string and wstring are specialized versions of basic_string for chars and wchar_ts, respectively.
This page describes the ANSI basic_string class. If you would like information on the pre-ANSI string class, use the command:
help cxxl
typedef basic_string <char> string; typedef basic_string <wchar_t> wstring;
SYNOPSIS
#include <string>
template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
class basic_string;
DESCRIPTION
basic_string<charT, traits, Allocator> is a homogeneous collection of character-like entities. It provides general string functionality such as compare, append, assign, insert, remove, and replace , along with various searches. basic_string also functions as an STL sequence container, providing random access iterators. This allows some of the generic algorithms to apply to strings.
Any underlying character-like type may be used as long as an appropriate string_char_traits class is provided or the default traits class is applicable.
INTERFACE
template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> > class basic_string {
public:
// Types
typedef traits traits_type; typedef typename traits::char_type value_type; typedef Allocator allocator_type;
typename size_type; typename difference_type; typename reference; typename const_reference; typename pointer; typename const_pointer; typename iterator; typename const_iterator; typename const_reverse_iterator; typename reverse_iterator;
static const size_type npos = -1;
// Constructors/Destructors
explicit basic_string(const Allocator& = Allocator()); basic_string (const basic_string<charT, traits, Allocator>&); basic_string(const basic_string&, size_type, size_type = npos); basic_string(const charT*, size_type, const Allocator& = Allocator()); basic_string(const charT*, Allocator& = Allocator()); basic_string(size_type, charT, const Allocator& = Allocator()); template <class InputIterator> basic_string(InputIterator, InputIterator, const Allocator& = Allocator()); ~basic_string();
// Assignment operators basic_string& operator=(const basic_string&); basic_string& operator=(const charT*); basic_string& operator=(charT);
// Iterators
iterator begin(); const_iterator begin() const; iterator end(); const_iterator end() const;
reverse_iterator rbegin(); const_reverse_iterator rbegin() const; reverse_iterator rend(); const_reverse_iterator rend() const;
// Capacity
size_type size() const; size_type length() const; size_type max_size() const; void resize(size_type, charT); void resize(size_type); size_type capacity() const; void reserve(size_type); bool empty() const;
// Element access
const_reference operator[](size_type) const; reference operator[](size_type); const_reference at(size_type) const; reference at(size_type);
// Modifiers
basic_string& operator+=(const basic_string&); basic_string& operator+=(const charT*); basic_string& operator+=(charT);
basic_string& append(const basic_string&); basic_string& append(const basic_string&, size_type, size_type); basic_string& append(const charT*, size_type); basic_string& append(const charT*); basic_string& append(size_type, charT); template<class InputIterator> basic_string& append(InputIterator, InputIterator);
basic_string& assign(const basic_string&); basic_string& assign(const basic_string&, size_type, size_type); basic_string& assign(const charT*, size_type); basic_string& assign(const charT*); basic_string& assign(size_type, charT); template<class InputIterator> basic_string& assign(InputIterator, InputIterator);
basic_string& insert(size_type, const basic_string&); basic_string& insert(size_type, const basic_string&, size_type, size_type); basic_string& insert(size_type, const charT*, size_type); basic_string& insert(size_type, const charT*); basic_string& insert(size_type, size_type, charT); iterator insert(iterator, charT = charT()); void insert(iterator, size_type, charT); template<class InputIterator> void insert(iterator, InputIterator, InputIterator);
basic_string& erase(size_type = 0, size_type= npos); iterator erase(iterator); iterator erase(iterator, iterator);
basic_string& replace(size_type, size_type, const basic_string&); basic_string& replace(size_type, size_type, const basic_string&, size_type, size_type); basic_string& replace(size_type, size_type, const charT*, size_type); basic_string& replace(size_type, size_type, const charT*); basic_string& replace(size_type, size_type, size_type, charT); basic_string& replace(iterator, iterator, const basic_string&); basic_string& replace(iterator, iterator, const charT*, size_type); basic_string& replace(iterator, iterator, const charT*); basic_string& replace(iterator, iterator, size_type, charT); template<class InputIterator> basic_string& replace(iterator, iterator, InputIterator, InputIterator);
size_type copy(charT*, size_type, size_type = 0); void swap(basic_string<charT, traits, Allocator>&);
// String operations
const charT* c_str() const; const charT* data() const; const allocator_type& get_allocator() const;
size_type find(const basic_string&, size_type = 0) const; size_type find(const charT*, size_type, size_type) const; size_type find(const charT*, size_type = 0) const; size_type find(charT, size_type = 0) const; size_type rfind(const basic_string&, size_type = npos) const; size_type rfind(const charT*, size_type, size_type) const; size_type rfind(const charT*, size_type = npos) const; size_type rfind(charT, size_type = npos) const;
size_type find_first_of(const basic_string&, size_type = 0) const; size_type find_first_of(const charT*, size_type, size_type) const; size_type find_first_of(const charT*, size_type = 0) const; size_type find_first_of(charT, size_type = 0) const;
size_type find_last_of(const basic_string&, size_type = npos) const; size_type find_last_of(const charT*, size_type, size_type) const; size_type find_last_of(const charT*, size_type = npos) const; size_type find_last_of(charT, size_type = npos) const;
size_type find_first_not_of(const basic_string&, size_type = 0) const; size_type find_first_not_of(const charT*, size_type, size_type) const; size_type find_first_not_of(const charT*, size_type = 0) const; size_type find_first_not_of(charT, size_type = 0) const;
size_type find_last_not_of(const basic_string&, size_type = npos) const; size_type find_last_not_of(const charT*, size_type, size_type) const; size_type find_last_not_of(const charT*, size_type = npos) const; size_type find_last_not_of(charT, size_type = npos) const;
basic_string substr(size_type = 0, size_type = npos) const; int compare(const basic_string&) const; int compare(size_type, size_type, const basic_string&) const; int compare(size_type, size_type, const basic_string&, size_type, size_type) const; int compare(size_type, size_type, charT*) const; int compare(charT*) const; int compare(size_type, size_type, const charT*, size_type) const; };
// Non-member Operators
template <class charT, class traits, class Allocator> basic_string operator+ (const basic_string&, const basic_string&); template <class charT, class traits, class Allocator> basic_string operator+ (const charT*, const basic_string&); template <class charT, class traits, class Allocator> basic_string operator+ (charT, const basic_string&); template <class charT, class traits, class Allocator> basic_string operator+ (const basic_string&, const charT*); template <class charT, class traits, class Allocator> basic_string operator+ (const basic_string&, charT);
template <class charT, class traits, class Allocator> bool operator== (const basic_string&, const basic_string&); template <class charT, class traits, class Allocator> bool operator== (const charT*, const basic_string&); template <class charT, class traits , class Allocator> bool operator== (const basic_string&, const charT*);
template <class charT, class traits, class Allocator> bool operator< (const basic_string&, const basic_string&); template <class charT, class traits, class Allocator> bool operator< (const charT*, const basic_string&); template <class charT, class traits, class Allocator> bool operator< (const basic_string&, const charT*);
template <class charT, class traits, class Allocator> bool operator!= (const basic_string&, const basic_string&); template <class charT, class traits, class Allocator> bool operator!= (const charT*, const basic_string&); template <class charT, class traits, class Allocator> bool operator!= (const basic_string&, const charT*);
template <class charT, class traits, class Allocator> bool operator> (const basic_&, const basic_string&); template <class charT, class traits, class Allocator> bool operator> (const charT*, const basic_string&); template <class charT, class traits, class Allocator> bool operator> (const basic_string&, const charT*);
template <class charT, class traits, class Allocator> bool operator<= (const basic_string&, const basic_string&); template <class charT, class traits, class Allocator> bool operator<= (const charT*, const basic_string&); template <class charT, class traits, class Allocator> bool operator<= (const basic_string&, const charT*);
template <class charT, class traits, class Allocator> bool operator>= (const basic_string&, const basic_string&); template <class charT, class traits, class Allocator> bool operator>= (const charT*, const basic_string&); template <class charT, class traits, class Allocator> bool operator>= (const basic_string&, const charT*);
template <class charT, class traits, class Allocator> void swap(basic_string<charT,traits,Allocator>& a, basic_string<charT,traits,Allocator>& b);
template<class charT, class traits, class Allocator> istream& operator>> (istream&, basic_string&); template <class charT, class traits, class Allocator> ostream& operator<< (ostream&, const basic_string&); template <class Stream, class charT, class traits, class Allocator> Stream& getline (Stream&, basic_string&, charT);
CONSTRUCTORS AND DESTRUCTORS
In all cases, the Allocator parameter will be used for storage management.
explicit basic_string (const Allocator& a = Allocator()); The default constructor. Creates a basic_string with the following effects:
data() a non-null pointer that is copyable and can have 0 added to it
size() 0
capacity() an unspecified value
basic_string (const basic_string<T, traits, Allocator>& str); Copy constructor. Creates a string that is a copy of str.
basic_string (const basic_string &str, size_type pos, size_type n= npos); Creates a string if pos<=size() and determines length rlen of initial string value as the smaller of n and str.size()- pos. This has the following effects:
data() points at the first element of an allocated copy of rlen elements of the string controlled by str beginning at position pos
size() rlen
capacity() a value at least as large as size()
get_allocator() str.get_allocator()
An out_of_range exception will be thrown if pos>str.size().
basic_string (const charT* s, size_type n, const Allocator& a = Allocator()); Creates a string that contains the first n characters of s. s must not be a NULL pointer. The effects of this constructor are:
data() points at the first element of an allocated copy of the array whose first element is pointed at by s
size() n
capacity() a value at least as large as size()
An out_of_range exception will be thrown if n == npos.
basic_string (const charT * s, const Allocator& a = Allocator()); Constructs a string containing all characters in s up to, but not including, a traits::eos() character. s must not be a null pointer. The effects of this constructor are:
data() points at the first element of an allocated copy of the array whose first element is pointed at by s
size() traits::length(s)
capacity() a value at least as large as size()
basic_string (size_type n, charT c, const Allocator& a = Allocator()); Constructs a string containing n repetitions of c. A length_error exception is thrown if n == npos. The effects of this constructor are:
data() points at the first element of an allocated array of n elements, each storing the initial value c
size() n
capacity() a value at least as large as size()
template <class InputIterator> basic_string (InputIterator first, InputIterator last, const Allocator& a = Allocator()); Creates a basic_string of length last - first, filled with all values obtained by dereferencing the InputIterators on the range [first, last). The effects of this constructor are:
data() points at the first element of an allocated copy of the elements in the range [first,last)
size() distance between first and last
capacity() a value at least as large as size()
~basic_string (); Releases any allocated memory for this basic_string.
OPERATORS
basic_string& operator= (const basic_string& str); Assignment operator. Sets the contents of this string to be the same as str. The effects of operator= are:
data() points at the first element of an allocated copy of the array whose first element is pointed at by str.size()
size() str.size()
capacity() a value at least as large as size()
basic_string& operator= (const charT * s); Assignment operator. Sets the contents of this string to be the same as s up to, but not including, the traits::eos() character.
basic_string& operator= (charT c); Assignment operator. Sets the contents of this string to be equal to the single charT c.
const_reference operator[] (size_type pos) const; reference operator[] (size_type pos); If pos < size(), returns the element at position pos in this string. If pos == size(), the const version returns traits::eos(), the behavior of the non-const version is undefined. The reference returned by either version is invalidated by any call to c_str(), data(), or any non-const member function for the object.
basic_string& operator+= (const basic_string& s); basic_string& operator+= (const charT* s); basic_string& operator+= (charT c); Concatenates a string onto the current contents of this string. The second member operator uses traits::length() to determine the number of elements from s to add. The third member operator adds the single character c. All return a reference to this string after completion.
ITERATORS
iterator begin (); const_iterator begin () const; Return an iterator initialized to the first element of the string.
iterator end (); const_iterator end () const; Return an iterator initialized to the position after the last element of the string.
reverse_iterator rbegin (); const_reverse_iterator rbegin () const; Returns an iterator equivalent to reverse_iterator(end()).
reverse_iterator rend (); const_reverse_iterator rend () const; Returns an iterator equivalent to reverse_iterator(begin()).
ALLOCATOR
const allocator_type get_allocator () const; Returns a copy of the allocator used by self for storage management.
MEMBER FUNCTIONS
basic_string& append (const basic_string& s, size_type pos, size_type npos); basic_string& append (const basic_string& s); basic_string& append (const charT* s, size_type n); basic_string& append (const charT* s); basic_string& append (size_type n, charT c ); template<class InputIterator> basic_string& append (InputIterator first, InputIterator last); Append another string to the end of this string. The first two functions append the lesser of n and s.size() - pos characters of s, beginning at position pos to this string. The second member will throw an out_of_range exception if pos > str.size(). The third member appends n characters of the array pointed to by s. The fourth variation appends elements from the array pointed to by s up to, but not including, a traits::eos() character. The fifth variation appends n repetitions of c. The final append function appends the elements specified in the range [first, last).
All functions will throw a length_error exception if the resulting length will exceed max_size(). All return a reference to this string after completion.
basic_string& assign (const basic_string& s); basic_string& assign (const basic_string& s, size_type pos, size_type n); basic_string& assign (const charT* s, size_type n); basic_string& assign (const charT* s); basic_string& assign (size_type n, charT c ); template<class InputIterator> basic_string& assign (InputIterator first, InputIterator last);
Replace the value of this string with the value of another.
All versions of the function assign values to this string. The first two variations assign the lesser of n and s.size() - pos characters of s, beginning at position pos. The second variation throws an out_of_range exception if pos > str.size(). The third version of the function assigns n characters of the array pointed to by s. The fourth version assigns elements from the array pointed to by s up to, but not including, a traits::eos() character. The fifth assigns one or n repetitions of c. The last variation assigns the members specified by the range [first, last).
All functions will throw a length_error exception if the resulting length will exceed max_size(). All return a reference to this string after completion.
const_reference at (size_type pos) const; reference at (size_type pos); If pos < size(), returns the element at position pos in this string. Otherwise, an out_of_range exception is thrown.
size_type capacity () const; Returns the current storage capacity of the string. This is guaranteed to be at least as large as size().
int compare (const basic_string& str); Returns the result of a lexicographical comparison between elements of this string and elements of str. The return value is:
<0 if size() < str.size() 0 if size() == str.size() >0 if size() > str.size()
int compare (size_type pos1, size_type n1, const basic_string& str) const; int compare (size_type pos1, size_type n1, const basic_string& str, size_type pos2, size_type n2) const; int compare (charT* s) const; int compare (size_type pos, size_type n1, charT* s) const; int compare (size_type pos, size_type n1, charT* s, size_type n2) const; Return the result of a lexicographical comparison between elements of this string and a given comparison string. The members return, respectively:
compare (str) compare (basic_string (str, pos2, n2)) compare (basic_string(s)) compare (basic_string(s, npos)) compare (basic_string (s,n2))
size_type copy (charT* s, size_type n, size_type pos = 0) const; Replaces elements in memory with copies of elements from this string. An out_of_range exception will be thrown if pos > size(). The lesser of n and size() - pos elements of this string, starting at position pos are copied into the array pointed to by s. No terminating null is appended to s.
const charT* c_str () const; const charT* data () const; Return a pointer to the initial element of an array whose first size() elements are copies of the elements in this string. A traits::eos() element is appended to the end. The elements of the array may not be altered, and the returned pointer is only valid until a non-const member function of this string is called. If size() is zero, the data() function returns a NULL pointer.
bool empty () const; Returns size() == 0.
basic_string& erase (size_type pos = 0, size_type n = npos); iterator erase (iterator p); iterator erase (iterator first, iterator last); This function removes elements from the string, collapsing the remaining elements, as necessary, to remove any space left empty. The first version of the function removes the smaller of n and size() - pos starting at position pos. An out_of_range exception will be thrown if pos > size(). The second version requires that p is a valid iterator on this string, and removes the character referred to by p. The last version of erase requires that both first and last are valid iterators on this string, and removes the characters defined by the range [first,last). The destructors for all removed characters are called. All versions of erase return a reference to this string after completion.
size_type find (const basic_string& str, size_type pos = 0) const; Searches for the first occurrence of the substring specified by str in this string, starting at position pos. If found, it returns the index of the first character of the matching substring. If not found, returns npos. Equality is defined by traits::eq().
size_type find (const charT* s, size_type pos, size_type n) const; size_type find (const charT* s, size_type pos = 0) const; size_type find (charT c, size_type pos = 0) const; Search for the first sequence of characters in this string that match a specified string. The variations of this function return, respectively:
find(basic_string(s,n), pos) find(basic_string(s), pos) find(basic_string(1, c), pos)
size_type find_first_not_of (const basic_string& str, size_type pos = 0) const; Searches for the first element of this string at or after position pos that is not equal to any element of str. If found, find_first_not_of returns the index of the non-matching character. If all of the characters match, the function returns npos. Equality is defined by traits::eq().
size_type find_first_not_of (const charT* s, size_type pos, size_type n) const; size_type find_first_not_of (const charT* s, size_type pos = 0) const; size_type find_first_not_of (charT c, size_type pos = 0) const; Search for the first element in this string at or after position pos that is not equal to any element of a given set of characters. The members return, respectively:
find_first_not_of(basic_string(s,n), pos) find_first_not_of(basic_string(s), pos) find_first_not_of(basic_string(1, c), pos)
size_type find_first_of(const basic_string& str, size_type pos = 0) const; Searches for the first occurrence at or after position pos of any element of str in this string. If found, the index of this matching character is returned. If not found, npos is returned. Equality is defined by traits::eq().
size_type find_first_of(const charT* s, size_type pos, size_type n) const; size_type find_first_of(const charT* s, size_type pos = 0) const; size_type find_first_of (charT c, size_type pos = 0) const; Search for the first occurrence in this string of any element in a specified string. The find_first_of variations return, respectively:
find_first_of(basic_string(s,n), pos) find_first_of(basic_string(s), pos) find_first_of(basic_string(1, c), pos)
size_type find_last_not_of(const basic_string& str, size_type pos = npos) const; Searches for the last element of this string at or before position pos that is not equal to any element of str. If find_last_not_of finds a non-matching element, it returns the index of the character. If all the elements match, the function returns npos. Equality is defined by traits::eq().
size_type find_last_not_of(const charT* s, size_type pos, size_type n) const; size_type find_last_not_of(const charT* s, size_type pos = npos) const; size_type find_last_not_of(charT c, size_type pos = npos) const; Search for the last element in this string at or before position pos that is not equal to any element of a given set of characters. The members return, respectively:
find_last_not_of(basic_string(s,n), pos) find_last_not_of(basic_string(s), pos) find_last_not_of(basic_string(1, c), pos)
size_type find_last_of(const basic_string& str, size_type pos = npos) const; Searches for the last occurrence of any element of str at or before position pos in this string. If found, find_last_of returns the index of the matching character. If not found find_last_of returns npos. Equality is defined by traits::eq().
size_type find_last_of(const charT* s, size_type pos, size_type n) const; size_type find_last_of(const charT* s, size_type pos = npos) const; size_type find_last_of(charT c, size_type pos = npos) const; Search for the last occurrence in this string of any element in a specified string. The members return, respectively:
find_last_of(basic_string(s,n), pos) find_last_of(basic_string(s), pos) find_last_of(basic_string(1, c), pos)
basic_string& insert(size_type pos1, const basic_string& s); basic_string& insert(size_type pos, const basic_string& s, size_type pos2 = 0, size_type n = npos); basic_string& insert(size_type pos, const charT* s, size_type n); basic_string& insert(size_type pos, const charT* s); basic_string& insert(size_type pos, size_type n, charT c); Insert additional elements at position pos in this string. All of the variants of this function will throw an out_of_range exception if pos > size(). All variants will also throw a length_error if the resulting string will exceed max_size(). Elements of this string will be moved apart as necessary to accommodate the inserted elements. All return a reference to this string after completion.
The second variation of this function inserts the lesser of n and s.size() - pos2 characters of s, beginning at position pos2 in this string. This version will throw an out_of_range exception if pos2 > s.size(). The third version inserts n characters of the array pointed to by s. The fourth inserts elements from the array pointed to by s up to, but not including, a traits::eos() character. Finally, the fifth variation inserts n repetitions of c.
iterator insert(iterator p, charT c = charT()); void insert(iterator p, size_type n, charT c); template<class InputIterator> void insert(iterator p, InputIterator first, InputIterator last); Insert additional elements in this string immediately before the character referred to by p. All of these versions of insert require that p is a valid iterator on this string. The first version inserts a copy of c. The second version inserts n repetitions of c. The third version inserts characters in the range [first, last). The first version returns p.
size_type length() const; Return the number of elements contained in this string.
size_type max_size() const; Returns the maximum possible size of the string.
size_type rfind (const basic_string& str, size_type pos = npos) const; Searches for the last occurrence of the substring specified by str in this string, starting at position pos. Note that only the first character of the substring must be <= pos; the remaining characters may extend beyond pos. If found, the index of the first character of that matches substring is returned. If not found, npos is returned. Equality is defined by traits::eq().
size_type rfind(const charT* s, size_type pos, size_type n) const; size_type rfind(const charT* s, size_type pos = npos) const; size_type rfind(charT c, size_type pos = npos) const; Searches for the last sequence of characters in this string matching a specified string. The rfind variations return, respectively:
rfind(basic_string(s,n), pos) rfind(basic_string(s), pos) rfind(basic_string(1, c), pos)
basic_string& replace(size_type pos, size_type n1, const basic_string& s); basic_string& replace(size_type pos1, size_type n1, const basic_string& str, size_type pos2, size_type n2); basic_string& replace(size_type pos, size_type n1, const charT* s, size_type n2); basic_string& replace(size_type pos, size_type n1, const charT* s); basic_string& replace(size_type pos, size_type n1, size_type n2, charT c); The replace function replaces selected elements of this string with an alternate set of elements. All of these versions insert the new elements in place of n1 elements in this string, starting at position pos. They each throw an out_of_range exception if pos1 > size()and a length_error exception if the resulting string size exceeds max_size().
The second version replaces elements of the original string with n2 characters from string s starting at position pos2. It will throw the out_of_range exception if pos2 > s.size(). The third variation of the function replaces elements in the original string with n2 elements from the array pointed to by s. The fourth version replaces elements in the string with elements from the array pointed to by s, up to, but not including, a traits::eos() character. The fifth replaces n elements with n2 repetitions of character c.
basic_string& replace(iterator i1, iterator i2, const basic_string& str); basic_string& replace(iterator i1, iterator i2, const charT* s, size_type n); basic_string& replace(iterator i1, iterator i2, const charT* s); basic_string& replace(iterator i1, iterator i2, size_type n, charT c); template<class InputIterator> basic_string& replace(iterator i1, iterator i2, InputIterator j1, InputIterator j2); Replace selected elements of this string with an alternative set of elements. All of these versions of replace require iterators i1 and i2 to be valid iterators on this string. The elements specified by the range [i1, i2) are replaced by the new elements.
The first version shown here replaces with all members in str. The second version starts at position i1, and replaces the next n characters with n characters of the array pointed to by s. The third variation replaces string elements with elements from the array pointed to by s up to, but not including, a traits::eos() character. The fourth version replaces string elements with n repetitions of c. The last variation shown here replaces string elements with the members specified in the range [j1, j2).
void reserve(size_type res_arg); Assures that the storage capacity is at least res_arg.
void resize(size_type n, charT c); void resize(size_type n); Changes the capacity of this string to n. If the new capacity is smaller than the current size of the string, then it is truncated. If the capacity is larger, then the string is padded with c characters. The latter resize member pads the string with default characters specified by traits::eos().
size type size() const; Return the number of elements contained in this string.
basic_string substr(size_type pos = 0, size_type n = npos) const; Returns a string composed of copies of the lesser of n and size() characters in this string starting at index pos. Throws an out_of_range exception if pos <= size().
void swap(basic_string& s); Swaps the contents of this string with the contents of s.
NON-MEMBER OPERATORS
template<class charT, class traits, class Allocator> basic_string operator+(const basic_string& lhs, const basic_string& rhs); Returns a string of length lhs.size() + rhs.size(), where the first lhs.size() elements are copies of the elements of lhs, and the next rhs.size() elements are copies of the elements of rhs.
template<class charT, class traits, class Allocator> basic_string operator+(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> basic_string operator+(charT lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> basic_string operator+(const basic_string& lhs, const charT* rhs); template<class charT, class traits, class Allocator> basic_string operator+(const basic_string& lhs, charT rhs); Returns a string that represents the concatenation of two string-like entities. These functions return, respectively:
basic_string(lhs) + rhs basic_string(1, lhs) + rhs lhs + basic_string(rhs) lhs + basic_string(1, rhs)
template<class charT, class traits, class Allocator> bool operator==(const basic_string& lhs, const basic_string& rhs); Returns a boolean value of true if lhs and rhs are equal, and false if they are not. Equality is defined by the compare() member function.
template<class charT, class traits, class Allocator> bool operator==(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> bool operator==(const basic_string& lhs, const charT* rhs); Returns a boolean value indicating whether lhs and rhs are equal. Equality is defined by the compare() member function. These functions return, respectively:
basic_string(lhs) == rhs lhs == basic_string(rhs)
template<class charT, class traits, class Allocator> bool operator!=(const basic_string& lhs, const basic_string& rhs); Returns a boolean value representing the inequality of lhs and rhs. Inequality is defined by the compare() member function.
template<class charT, class traits, class Allocator> bool operator!=(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> bool operator!=(const basic_string& lhs, const charT* rhs); Returns a boolean value representing the inequality of lhs and rhs. Inequality is defined by the compare() member function. The functions return, respectively:
basic_string(lhs) != rhs lhs != basic_string(rhs)
template<class charT, class traits, class Allocator> bool operator<(const basic_string& lhs, const basic_string& rhs); Returns a boolean value representing the lexicographical less-than relationship of lhs and rhs. Less-than is defined by the compare() member.
template<class charT, class traits, class Allocator> bool operator<(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> bool operator<(const basic_string& lhs, const charT* rhs); Returns a boolean value representing the lexicographical less-than relationship of lhs and rhs. Less-than is defined by the compare() member function. These functions return, respectively:
basic_string(lhs) < rhs lhs < basic_string(rhs)
template<class charT, class traits, class Allocator> bool operator>(const basic_string& lhs, const basic_string& rhs); Returns a boolean value representing the lexicographical greater-than relationship of lhs and rhs. Greater-than is defined by the compare() member function.
template<class charT, class traits, class Allocator> bool operator>(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> bool operator>(const basic_string& lhs, const charT* rhs); Returns a boolean value representing the lexicographical greater-than relationship of lhs and rhs. Greater-than is defined by the compare() member. The functions return, respectively:
basic_string(lhs) > rhs lhs > basic_string(rhs)
template<class charT, class traits, class Allocator> bool operator<=(const basic_string& lhs, const basic_string& rhs); Returns a boolean value representing the lexicographical less-than-or-equal relationship of lhs and rhs. Less-than-or-equal is defined by the compare() member function.
template<class charT, class traits, class Allocator> bool operator<=(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> bool operator<=(const basic_string& lhs, const charT* rhs); Returns a boolean value representing the lexicographical less-than-or-equal relationship of lhs and rhs. Less-than-or-equal is defined by the compare() member function. These functions return, respectively:
basic_string(lhs) <= rhs lhs <= basic_string(rhs)
template<class charT, class traits, class Allocator> bool operator>=(const basic_string& lhs, const basic_string& rhs); Returns a boolean value representing the lexicographical greater-than-or-equal relationship of lhs and rhs. Greater-than-or-equal is defined by the compare() member function.
template<class charT, class traits, class Allocator> bool operator>=(const charT* lhs, const basic_string& rhs); template<class charT, class traits, class Allocator> bool operator>=(const basic_string& lhs, const charT* rhs); Returns a boolean value representing the lexicographical greater-than-or-equal relationship of lhs and rhs. Greater-than-or-equal is defined by the compare() member. The functions return, respectively:
basic_string(lhs) >= rhs lhs >= basic_string(rhs)
template <class charT, class traits, class Allocator> void swap(basic_string<charT,traits,Allocator>& a, basic_string<charT,traits,Allocator>& b); Swaps the contents of a and b by calling a's swap function on b.
template<class charT, class traits, class Allocator> istream& operator>>(istream& is, basic_string& str); Reads str from is using traits::char_in until a traits::is_del() element is read. All elements read, except the delimiter, are placed in str. After the read, the function returns is.
template<class charT, class traits, class Allocator> ostream& operator<<(ostream& os, const basic_string& str); Writes all elements of str to os in order from first to last, using traits::char_out(). After the write, the function returns os.
NON-MEMBER FUNCTION
template <class Stream, class charT, class traits, class Allocator> Stream& getline(Stream& is, basic_string& str, charT delim); An unformatted input function that extracts characters from is into str until npos - 1 characters are read, the end of the input sequence is reached, or the character read is delim. The characters are read using traits::char_in().
EXAMPLE
// // string.cpp // #include<string> #include <iostream.h>
int main() { string test;
//Type in a string over five characters long while(test.empty() || test.size() <= 5) { cout << "Type a string between 5 and 100 characters long. " << endl; cin >> test; }
//Test operator[] access cout << "Changing the third character from " << test[2] << " to * " << endl; test[2] = '*'; cout << "now its: " << test << endl << endl;
//Try the insertion member function cout << "Identifying the middle: "; test.insert(test.size() / 2, "(the middle is here!)"); cout << test << endl << endl;
//Try replacement cout << "I didn't like the word 'middle',so instead,I'll say:" << endl; test.replace(test.find("middle",0), 6, "center"); cout << test << endl;
return 0; }
Output : Type a string between 5 and 100 characters long. roguewave Changing the third character from g to * now its: ro*uewave Identifying the middle: ro*u(the middle is here!)ewave I didn't like the word 'middle', so instead, I'll say: ro*u(the center is here!)ewave
SEE ALSO
Allocators, string, wstring
STANDARDS CONFORMANCE ANSI X3J16/ISO WG21 Joint C++ Committee
basic_stringbuf
Standard C++ Library Copyright 1996, Rogue Wave Software, Inc.NAME
basic_stringbuf
SYNOPSIS
#include <sstream> template<class charT, class traits = char_traits<charT>, class Allocator = allocator<void> > class basic_stringbuf : public basic_streambuf<charT, traits>
DESCRIPTION
The class basic_stringbuf is derived from basic_streambuf. Its purpose is to associate the input or output sequence with a sequence of arbitrary characters. The sequence can be initialized from, or made available as, an object of class basic_string. Each object of type basic_stringbuf<charT,traits,Allocator> controls two character sequences:
+ A character input sequence;
+ A character output sequence.
Note: see basic_streambuf.
The two sequences are related to each other, but are manipulated separately. This allows you to read and write characters at different positions in objects of type basic_stringbuf without any conflict (as opposed to the basic_filebuf objects, in which a joint file position is maintained).
INTERFACE
template<class charT, class traits = char_traits<charT>, class allocator<void> > class basic_stringbuf : public basic_streambuf<charT, traits> {
public:
typedef basic_ios<charT, traits> ios_type;
typedef basic_string<charT, traits, Allocator> string_type;
typedef charT char_type; typedef typename traits::int_type int_type; typedef typename traits::pos_type pos_type; typedef typename traits::off_type off_type;
explicit basic_stringbuf(ios_base::openmode which = (ios_base::in | ios_base::out));
explicit basic_stringbuf(const string_type& str, ios_base::openmode which = (ios_base::in | ios_base::out));
virtual ~basic_stringbuf();
string_type str() const; void str(const string_type& str_arg);
protected:
virtual int_type overflow(int_type c = traits::eof());
virtual int_type pbackfail(int_type c = traits::eof());
virtual int_type underflow();
virtual basic_streambuf<charT,traits>* setbuf(char_type *s,streamsize n);
virtual pos_type seekoff(off_type off, ios_base::seekdir way, ios_base::openmode which = ios_base::in | ios_base::out);
virtual pos_type seekpos(pos_type sp, ios_base::openmode which = ios_base::in | ios_base::out);
virtual streamsize xsputn(const char_type* s, streamsize n);
};
TYPES
char_type The type char_type is a synonym for the template parameter charT.
ios_type The type ios_type is an instantiation of class basic_ios on type charT.
off_type The type off_type is a synonym of type traits::off_type.
pos_type The type pos_type is a synonym of type traits::pos_type.
string_type The type string_type is an instantiation of class basic_string on type charT.
stringbuf The type stringbuf is an instantiation of class basic_stringbuf on type char:
typedef basic_stringbuf<char> stringbuf;
traits_type The type traits_type is a synonym for the template parameter traits.
wstringbuf The type wstringbuf is an instantiation of class basic_stringbuf on type wchar_t:
typedef basic_stringbuf<wchar_t> wstringbuf;
CONSTRUCTORS
explicit basic_stringbuf(ios_base::openmode which = ios_base::in | ios_base::out); Constructs an object of class basic_stringbuf, initializing the base class with basic_streambuf(), and initializing the open mode with which.
explicit basic_stringbuf(const string_type& str, ios_base::openmode which = ios_base::in | ios_base::out); Constructs an object of class basic_stringbuf, initializing the base class with basic_streambuf(), and initializing the open mode with which. The string object str is copied to the underlying buffer. If the opening mode is in, initialize the input sequence to point at the first character of the buffer. If the opening mode is out, it initializes the output sequence to point at the first character of the buffer. If the opening mode is out | app, it initializes the output sequence to point at the last character of the buffer.
DESTRUCTOR
virtual ~basic_stringbuf(); Destroys an object of class basic_stringbuf.
MEMBER FUNCTIONS
int_type overflow(int_type c = traits::eof() ); If the output sequence has a put position available, and c is not traits::eof(), then this functions writes c into it. If there is no position available, the function increases the size of the buffer by allocating more memory and then writes c at the new current put position. If the operation fails, the function returns traits::eof(). Otherwise it returns traits::not_eof(c).
int_type pbackfail( int_type c = traits::eof() ); Puts back the character designated by c into the input sequence. If traits::eq_int_type(c,traits::eof()) returns true, the function moves the input sequence one position backward. If the operation fails, the function returns traits::eof(). Otherwise it returns traits::not_eof(c).
pos_type seekoff(off_type off, ios_base::seekdir way, ios_base::openmode which = ios_base::in | ios_base::out); If the open mode is in | out, this function alters the stream position of both the input and the output sequences. If the open mode is in, it alters the stream position of only the input sequence, and if it is out, it alters the stream position of the output sequence. The new position is calculated by combining the two parameters off (displacement) and way (reference point). If the current position of the sequence is invalid before repositioning, the operation fails and the return value is pos_type(off_type(-1)). Otherwise the function returns the current new position.
pos_type seekpos(pos_type sp,ios_base::openmode which = ios_base::in | ios_base::out); If the open mode is in | out, seekpos() alters the stream position of both the input and the output sequences. If the open mode is in, it alters the stream position of the input sequence only, and if the open mode is out, it alters the stream position of the output sequence only. If the current position of the sequence is invalid before repositioning, the operation fails and the return value is pos_type(off_type(-1)). Otherwise the function returns the current new position.
basic_streambuf<charT,traits>* setbuf(char_type*s, streamsize n); If the string buffer object is opened in output mode, proceed as follows:
if s is not a null pointer and n is greater than the content of the current buffer, replace it (copy its contents) by the buffer of size n pointed at by s. In the case where s is a null pointer and n is greater than the content of the current buffer, resize it to size n. If the function fails, it returns a null pointer.
string_type str() const; Returns a string object of type string_type whose content is a copy of the underlying buffer contents.
void str(const string_type& str_arg); Clears the underlying buffer and copies the string object str_arg into it. If the opening mode is in, initializes the input sequence to point at the first character of the buffer. If the opening mode is out, the function initializes the output sequence to point at the first character of the buffer. If the opening mode is out | app, it initializes the out- put sequence to point at the last character of the buffer.
int_type underflow(); If the input sequence has a read position available, the function returns the contents of this position. Otherwise it tries to expand the input sequence to match the output sequence and if possible returns the content of the new current position. The function returns traits::eof() to indicate failure.
streamsize xsputn(const char_type* s, streamsize n); Writes up to n characters to the output sequence. The characters written are obtained from successive elements of the array whose first element is designated by s. The function returns the number of characters written.
EXAMPLES
// // stdlib/examples/manual/stringbuf.cpp // #include<iostream> #include<sstream> #include<string>
void main ( ) { using namespace std;
// create a read/write string-stream object on tiny char // and attach it to an ostringstream object ostringstream out_1(ios_base::in | ios_base::out);
// tie the istream object to the ostringstream object istream in_1(out_1.rdbuf());
// output to out_1 out_1 << "Here is the first output";
// create a string object on tiny char string string_ex("l'heure est grave !");
// open a read only string-stream object on tiny char // and initialize it istringstream in_2(string_ex);
// output in_1 to the standard output cout << in_1.str() << endl;
// output in_2 to the standard output cout << in_2.rdbuf() << endl;
// reposition in_2 at the beginning in_2.seekg(0);
stringbuf::pos_type pos;
// get the current put position // equivalent to // out_1.tellp(); pos = out_1.rdbuf()->pubseekoff(0,ios_base::cur, ios_base::out);
// append the content of stringbuffer // pointed at by in_2 to the one // pointed at by out_1 out_1 << ' ' << in_2.rdbuf();
// output in_1 to the standard output cout << in_1.str() << endl;
// position the get sequence // equivalent to // in_1.seekg(pos); in_1.rdbuf()->pubseekpos(pos, ios_base::in);
// output "l'heure est grave !" cout << in_1.rdbuf() << endl << endl; }
SEE ALSO
char_traits, ios_base, basic_ios, basic_streambuf, basic_string, basic_istringstream, basic_ostringstream, basic_stringstream
Working Paper for Draft Proposed International Standard for Information Systems--Programming Language C++, Section 27.7.1
STANDARDS CONFORMANCE ANSI X3J16/ISO WG21 Joint C++ Committee
|
