GetProcAddress

The GetProcAddress function retrieves the address of the specified exported dynamic-link library (DLL) function.

FARPROC GetProcAddress(
  HMODULE hModule,    // handle to DLL module
  LPCSTR lpProcName   // function name
);

Parameters

hModule

[in] Handle to the DLL module that contains the function. The LoadLibrary or GetModuleHandle function returns this handle.

lpProcName

[in] Pointer to a null-terminated string containing the function name, or specifies the function's ordinal value. If this parameter is an ordinal value, it must be in the low-order word; the high-order word must be zero.

Return Values

If the function succeeds, the return value is the address of the DLL's exported function.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The GetProcAddress function is used to retrieve addresses of exported functions in DLLs.

The spelling and case of the function name pointed to by lpProcName must be identical to that in the EXPORTS statement of the source DLL's module-definition (.DEF) file. The exported names of Win32 API functions may differ from the names you use when calling these functions in your code. This difference is hidden by macros used in the SDK header files. For more information, see Win32 Function Prototypes.

The lpProcName parameter can identify the DLL function by specifying an ordinal value associated with the function in the EXPORTS statement. GetProcAddress verifies that the specified ordinal is in the range 1 through the highest ordinal value exported in the .DEF file. The function then uses the ordinal as an index to read the function's address from a function table. If the .DEF file does not number the functions consecutively from 1 to N (where N is the number of exported functions), an error can occur where GetProcAddress returns an invalid, non-NULL address, even though there is no function with the specified ordinal.

In cases where the function may not exist, the function should be specified by name rather than by ordinal value.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Winbase.h; include Windows.h.
  Library: Use Kernel32.lib.

See Also

Dynamic-Link Libraries Overview, Dynamic-Link Library Functions, FreeLibrary, GetModuleHandle, LoadLibrary