不同编译器返回不同类型
/*------------ miscellaneous -----------------------------------------------*/
/**
?* Linkage specification macro
?*/
#if !defined(PTAPI_DLL)
?#if defined(BUILD_PTAPI_DLL)
??#if defined(_MSC_VER)
??????????? #if defined(PTAPI_STATIC)
??????????????? #if defined __cplusplus
??????????????????? #define PTAPI_DLL extern "C"
??????????????? #else
??????????????????? #define PTAPI_DLL
??????????????? #endif
??????????? #else
??????????????? #if defined __cplusplus
??????????????????? #define PTAPI_DLL extern "C"
??????????????? #else
??????????????????? #define PTAPI_DLL extern
??????????????? #endif
??????????? #endif
??#elif defined(__SYMBIAN32__)
???#if defined(__cplusplus)
????#define PTAPI_DLL extern"C" EXPORT_C
???#else
????#define PTAPI_DLL EXPORT_C
???#endif
??#else
???#if defined(__cplusplus)
????#define PTAPI_DLL extern"C"
???#else
????#define PTAPI_DLL
???#endif
??#endif
?#else
??#if defined(_MSC_VER)
??????????? #if defined(PTAPI_STATIC)
??????????????? #if defined __cplusplus
??????????????????? #define PTAPI_DLL extern "C"
??????????????? #else
??????????????????? #define PTAPI_DLL
??????????????? #endif
??????????? #else???
??? ???#if defined __cplusplus
???? ???#define PTAPI_DLL extern "C" __declspec(dllimport)
????? ?#else
?????? ?#define PTAPI_DLL __declspec(dllimport)
?????? #endif
??????????? #endif
??#elif defined(__SYMBIAN32__)
???#if defined(__cplusplus)
????#define PTAPI_DLL extern"C" IMPORT_C
???#else
????#define PTAPI_DLL IMPORT_C
???#endif
??#else
???#if defined(__cplusplus)
????#define PTAPI_DLL extern"C"
???#else
????#define PTAPI_DLL
???#endif
??#endif
?#endif
#endif
?
/**
?* Macro for standard call convention
?*/
#ifndef PTAPI
#if defined(_MSC_VER)
#if defined(_DOS)
#define PTAPI far
#else
#define PTAPI __stdcall
#endif
#else
#define PTAPI
#endif
#endif
?
/*
nothing doing macros used for better documenting parameter specification
*/
/**
?* This is a definition which has sole purpose of
?* helping readability.? It indicates that formal
?* parameter is an input parameter.
?*/
#ifndef IN
#define IN
#endif
/**
?* This is a definition which has sole purpose of
?* helping readability.? It indicates that formal
?* parameter is an output parameter.?
?*/
#ifndef OUT
#define OUT
#endif
/**
?* This is a definition which has sole purpose of
?* helping readability.? It indicates that formal
?* parameter is both input and output parameter.?
?*/
#ifndef INOUT
#define INOUT
#endif
/**
?* This is a definition which has sole purpose of
?* helping readability.? It indicates that formal
?* parameter is an optional parameter.?
?*/
#ifndef OPTIONAL
#define OPTIONAL
#endif
某个.h文件中有这样一段
?
然后.c文件中有PTAPI_DLL ?PT_STATUS? PTAPI? PTOpen（。。形参。。。）{。函数体。。}
?
经查定义处发现PTAPI_DLL ?PT_STATUS? PTAPI只有一个是被定义成long型，其他的均定义为空。经请教别人得知，是为了在不同编译器下返回不同的值。PTAPI_DLL ?PT_STATUS? PTAPI只有一个是有效的。
