'HCRYPTHASH' : undeclared identifier 类似错误的解决办法

在编译一个cpp程序时，明明已经 include <wincrypt.h>，可还是报错 D:\crypt\crypt.cpp(20) : error C2065: 'HCRYPTHASH' : undeclared identifier D:\crypt\crypt.cpp(20) : error C2146: syntax error : missing ';' before identifier 'hHash' D:\crypt\crypt.cpp(20) : error C2065: 'hHash' : undeclared identifier D:\crypt\crypt.cpp(22) : error C2065: 'HCRYPTKEY' : undeclared identifier D:\crypt\crypt.cpp(22) : error C2146: syntax error : missing ';' before identifier 'hKey' D:\crypt\crypt.cpp(22) : error C2065: 'hKey' : undeclared identifier D:\crypt\crypt.cpp(24) : error C2065: 'HCRYPTPROV' : undeclared identifier D:\crypt\crypt.cpp(24) : error C2146: syntax error : missing ';' before identifier 'hProv' D:\crypt\crypt.cpp(24) : error C2065: 'hProv' : undeclared identifier D:\crypt\crypt.cpp(32) : error C2065: 'CryptAcquireContext' : undeclared identifier D:\crypt\crypt.cpp(38) : error C2065: 'CryptCreateHash' : undeclared identifier D:\crypt\crypt.cpp(54) : error C2065: 'CryptHashData' : undeclared identifier D:\crypt\crypt.cpp(70) : error C2065: 'CryptDeriveKey' : undeclared identifier D:\crypt\crypt.cpp(105) : error C2065: 'CryptEncrypt' : undeclared identifier D:\crypt\crypt.cpp(151) : error C2065: 'CryptDestroyHash' : undeclared identifier D:\crypt\crypt.cpp(157) : error C2065: 'CryptDestroyKey' : undeclared identifier 原因是： vc6缺省是不定义_WIN32_WINNT宏的。  而在wincrypt.h中有  #if (_WIN32_WINNT >= 0x0400)  ...  #endif 解决办法是： 在stdafx.h中添加 #ifndef   _WIN32_WINNT  #define   _WIN32_WINNT   0x0400  #endif