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Searching and Sorting Utilities
Searches an array of nmemb objects for an element that matches the object pointed to by key. The first element of the array is pointed to by base; the size of each element is specified by size.
Sorts an array of nmemb objects in place. The first element of the array is pointed to by base; the size of each element is specified by size. Returns the absolute value of an integer j. div_t div(int numer, int denom); Computes the quotient and remainder of the division of numer by denom. The div function returns a structure of type div_t containing the quotient and remainder: Returns the absolute value of a long integer j. ldiv_t ldiv(long int numer, long int denom); Similar to the div function, except that the arguments and the members of the returned structure (which has type ldiv_t ) all have type long int . int mblen(const char *s, size_t n); If s is not a null pointer, mblen determines the number of bytes comprising the multibyte character pointed to by s. The mblen function is equivalent to the following, except that the shift state of the mbtowc is not affected: int mbtowc(wchar_t *pwc, const char *s, size_t n); If s is not a null pointer, mbtowc determines the number of bytes comprising the multibyte character pointed to by s. It then determines the code for the value of type wchar_t that corresponds to that multibyte character. (The value of the code corresponding to the null character is 0.) If the multibyte character is valid and pwc is not a null pointer, mbtowc stores the code in the object pointed to by pwc. At most, n bytes of the array pointed to by s are examined. int wctomb(char *s, wchar_t wchar); Determines the number of bytes needed to represent the multibyte character corresponding to the code whose value is wchar, including any change in shift state. This function then stores the multibyte character representation in the array object pointed to by s, if s is not a null pointer. At most, MB_CUR_MAX characters are stored. If the value of wchar is 0, the wctomb function is left in the initial shift state. size_t mbstowcs(wchar_t *pwcs, const char *s, size_t n); Converts a sequence of multibyte characters that begin in the initial shift state from the array pointed to by s into a sequence of corresponding codes, and stores not more than n codes into the array pointed to by pwcs. A null character is converted to a code value of zero. No multibyte characters that follow a null character are examined or converted. Each multibyte character is converted as if by a call to mbtowc , except that the shift state of mbtowc is not affected. size_t wcstombs(char *s, const wchar_t *pwcs, size_t n); Converts a sequence of codes that correspond to multibyte characters from the array pointed to by pwcs into a sequence of multibyte characters that begins in the initial shift state, and stores these multibyte characters into the array pointed to by s. The conversion stops if a multibyte character would exceed the limit of n total bytes or if a null character is stored. 9.15 String Processing (<string.h>)The <string.h> header file declares one type and several functions, and defines one macro useful for manipulating character arrays that other objects treat as character arrays. There are two kinds of string functions declared. The first, with names beginning with str , manipulate character arrays; the second, with names beginning with mem , manipulate other objects treated as character arrays. Except for memmove , function behavior is undefined if copying takes place between overlapping objects. An unsigned integral type of the result of the sizeof operator. NULL Expands to an implementation-defined null pointer constant. void *memcpy(void *s1, const void *s2, size_t n); Copies n characters from the object pointed to by s2 to the object pointed to by s1. The function returns s1. void *memmove(void *s1, const void *s2, size_t n); Copies n characters from the object pointed to by s2 to the object pointed to by s1. Copying takes place as if the n characters from the object pointed to by s2 are first copied into a temporary array of n characters that does not overlap the object pointed to by s1 and s2, and then the n characters from the temporary array are copied into the object pointed to by s1. The memmove function returns s1. void *memchr(const void *s, int c, size_t n); Locates the first occurrence of c (converted to an unsigned char ) in the first n unsigned characters of the object pointed to by s. The memchr function returns a pointer to the located character, or a null pointer if the character was not found. int memcmp(const void *s1, const void *s2, size_t n); Compares the first n characters of the object pointed to by s1 to the first n characters of the object pointed to by s2. The memcmp function returns an integer less than, equal to, or greater than 0, depending on whether the object pointed to by s1 is less than, equal to, or greater than the object pointed to by s2. void *memset(void *s, int c, size_t n); Copies the value of c (converted to an unsigned char) into each of the first n characters pointed to by s. The function returns s. char *strcpy(char *s1, const char *s2); Copies the string pointed to by s2 (including the terminating null character) to the string pointed to by s1. The strcpy function returns s1. char *strncpy(char *s1, const char *s2, size_t n); Copies no more than n characters from the string pointed to by s2 to the string pointed to by s1, up to but not including the null terminator of the string pointed to by s2; returns s1. If the string pointed to by s2 is less than n characters, strncpy pads the copy with null characters. char *strcat(char *s1, const char *s2); Appends a copy of the the string pointed to by s2 (including the terminating null character) to the end of the string pointed to by s1. The strcat function returns s1. The first character of s2 overwrites the null character of s1. char *strncat(char *s1, const char *s2, size_t n); Appends no more than n characters from the string pointed to by s2 (up to but not including a null character) to the string pointed to by s1. The strncat function returns s1. The first character of s2 overwrites the null character of s1. A terminating null character is appended to the result. The first character of s2 overwrites the null character of s1. int strcmp(const char *s1, const char *s2); Compares the string pointed to by s1 to the string pointed to by s2. The strcmp function returns an integer less than, equal to, or greater than 0, depending on whether the string pointed to by s1 is less than, equal to, or greater than the string pointed to by s2. int strcoll(const char *s1, const char *s2); Compares the string pointed to by s1 to the string pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the current locale (see Section 9.6). The strcoll function returns an integer less than, equal to, or greater than 0, depending on whether the string pointed to by s1 is less than, equal to, or greater than the string pointed to by s2, when both are interpreted as appropriate to the current locale. int strncmp(const char *s1, const char *s2, size_t n); Compares no more than n characters from the string pointed to by s1 to the string pointed to by s2. The strings are compared until a null character is encountered, the strings differ, or n is reached. The strncmp function returns an integer less than, equal to, or greater than 0, depending on whether the string pointed to by s1 is less than, equal to, or greater than the string pointed to by s2. size_t strxfrm(char *s1, const char *s2, size_t n); Transforms the string pointed to by s2 and places the resulting string into the array pointed to by s1. char *strchr(const char *s, int c); Locates the first occurrence of c (converted to a char ) in the string pointed to by s. The terminating null character is considered to be part of the string. The function returns a pointer to the located character, or a null pointer if the character was not found. size_t strcspn(const char *s1, const char *s2); Computes the length of the maximum initial segment of the string pointed to by s1 that consists entirely of characters not found in the string pointed to by s2. The strcspn function returns the length of the segment. char *strpbrk(const char *s1, const char *s2); Locates the first occurrence in the string pointed to by s1 of any character from the string pointed to by s2. The function returns a pointer to the character, or a null pointer if no character in s1 occurs in s2. char *strrchr(const char *s, int c); Locates the last occurrence of c (converted to a char ) in the string pointed to by s. The terminating null character is considered to be part of the string. The function returns a pointer to the located character, or a null pointer if the character was not found. size_t strspn(const char *s1, const char *s2); Computes the length of the maximum initial segment of the string pointed to by s1 that consists entirely of characters from the string pointed to by s2. The strspn function returns the length of the segment. char *strstr(const char *s1, const char *s2); Locates the first occurrence in the string pointed to by s1 of the sequence of characters (excluding the terminal null character) in the string pointed to by s2. The strstr function returns a pointer to the located string, or a null pointer if the string was not found. If s2 points to a string of zero length, the function returns s1. char *strtok(const char *s1, char *s2); Breaks the string pointed to by s1 into a sequence of tokens, each of which is delimited by a character from the string pointed to by s2. The first call to strtok () skips characters, looking for the first one that is not in s2. The function keeps track of its position in the string pointed to by s1 between calls and, as successive calls are made, the function works through this string, identifying the text token following the one identified by the previous call. When the function finds a character in s1 that matches a character in s2, it replaces the character in s1 with a null character. The strtok function returns a pointer to the first character of the token, or a null pointer if there is no token. Maps the error number in errnum to an error message string; returns a pointer to the string. The string pointed to must not be modified by the program, but can be overwritten by a subsequent call to strerror . Computes the length of the string pointed to by s. The function returns the number of characters that precede the terminating null character. 9.16 Type-generic Math (<tgmath.h>)The header <tgmath.h> includes the headers <math.h> and <complex.h> and defines several type-generic macros. Of the <math.h> and <complex.h> functions without an f ( float ) or l ( long double ) suffix, several have one or more parameters whose corresponding real type is double . For each such function, except modf , there is a corresponding type-generic macro.1 The parameters whose corresponding real type is double in the function synopsis are generic parameters. Use of the macro invokes a function whose corresponding real type and type domain are determined by the arguments for the generic parameters.2
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