IDL-to-C Mappings

The Interface Definition Language (IDL) compiler converts an interface definition into output files. The rpc_intro(1rpc) reference page in the OSF DCE Command Reference contains a summary of the idl command, which invokes the IDL compiler.

Additional information about the IDL compiler appears in the following table, which shows the IDL base types and the IDL-to-C mappings.

The following table lists the IDL base data type specifiers. Where applicable, the table shows the size of the corresponding transmittable type and the type macro emitted by the IDL compiler for resulting declarations.

Base Data Type Specifiers - - rpc_intro(3rpc)

Specifier
(sign) (size) (type)

Size Type Macro Emitted by idl

small int 8 bits idl_small_int

short int 16 bits idl_short_int

long int 32 bits idl_long_int

hyper int 64 bits idl_hyper_int

unsigned small int 8 bits idl_usmall_int

unsigned short int 16 bits idl_ushort_int

unsigned long int 32 bits idl_ulong_int

unsigned hyper int 64 bits idl_uhyper_int

float 32 bits idl_short_float

double 64 bits idl_long_float

char 8 bits idl_char

boolean 8 bits idl_boolean

byte 8 bits idl_byte

void - idl_void_p_t

handle_t - -

Note that you can use the idl_ macros in the code you write for an application to ensure that your type declarations are consistent with those in the stubs, even when the application is ported to another platform. The idl_ macros are especially useful when passing constant values to RPC calls. For maximum portability, all constants passed to RPC calls declared in your network interfaces should be cast to the appropriate type because the size of integer constants (like the size of the int data type) is unspecified in the C language.

The idl_ macros are defined in dce/idlbase.h, which is included by header files that the IDL compiler generates.