C++ API - learn item1

1. GetModuleFileName Function

Retrieves the fully-qualified path for the file that contains the specified module. The module must have been loaded by the current process.
To locate the file for a module that was loaded by another process, use the GetModuleFileNameEx function.

Syntax

Copy

DWORD WINAPI GetModuleFileName(
  __in_opt  HMODULE hModule,
  __out     LPTSTR lpFilename,
  __in      DWORD nSize
); 

If this parameter is NULL, 
GetModuleFileName retrieves the path of the executable file of the current process.

2. strrchr, wcsrchr, _mbsrchr

Scan a string for the last occurrence of a character.

char *strrchr(
   const char *string,
   int c 
);
wchar_t *wcsrchr(
   const wchar_t *string,
   wchar_t c 
);
unsigned char *_mbsrchr(
   const unsigned char *string,
   unsigned int c 
);

Parameters

string

Null-terminated string to search.

c

Character to be located.

Return Value

Returns a pointer to the last occurrence of c in string, or NULL if c is not found.


sample:
    // Get the executable file's full path
    ::GetModuleFileNameA(NULL, sPath, MAX_PATH);
    //delete file name, just leave the folder
    char* p = ::strrchr(dir, '\\');
    *(p + 1) = 0;

3.strcat_s, wcscat_s, _mbscat_s

 Append a string. These are versions of strcat, wcscat, _mbscat with security enhancements as described in Security Enhancements in the CRT.

errno_t strcat_s(
   char *strDestination,
   size_t numberOfElements,
   const char *strSource 
);
errno_t wcscat_s(
   wchar_t *strDestination,
   size_t numberOfElements,
   const wchar_t *strSource 
);
errno_t _mbscat_s(
   unsigned char *strDestination,
   size_t numberOfElements,
   const unsigned char *strSource 
);
template <size_t size>
errno_t strcat_s(
   char (&strDestination)[size],
   const char *strSource 
); // C++ only
template <size_t size>
errno_t wcscat_s(
   wchar_t (&strDestination)[size],
   const wchar_t *strSource 
); // C++ only
template <size_t size>
errno_t _mbscat_s(
   unsigned char (&strDestination)[size],
   const unsigned char *strSource 
); // C++ only

Parameters

strDestination

Null-terminated destination string buffer.

numberOfElements

Size of the destination string buffer.

strSource

Null-terminated source string buffer.

4.FindFirstFile Function

Searches a directory for a file or subdirectory with a name that matches a specific name (or partial name if wildcards are used).
To specify additional attributes to use in a search, use the FindFirstFileEx function.
To perform this operation as a transacted operation, use the FindFirstFileTransacted function.

Syntax

HANDLE WINAPI FindFirstFile(
  __in   LPCTSTR lpFileName,
  __out  LPWIN32_FIND_DATA lpFindFileData
);

Parameters

lpFileName [in]

The directory or path, and the file name, which can include wildcard characters, for example, an asterisk (*) or a question mark (?).

This parameter should not be NULL, an invalid string (for example, an empty string or a string that is missing the terminating null character), or end in a trailing backslash (\). If the string ends with a wildcard, period (.), or directory name, the user must have access permissions to the root and all subdirectories on the path. In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 widecharacters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming a File.

lpFindFileData [out]

A pointer to the WIN32_FIND_DATA structure that receives information about a found file or directory.

Return Value

If the function succeeds, the return value is a search handle used in a subsequent call to FindNextFile or FindClose, and the lpFindFileData parameter contains information about the first file or directory found.
If the function fails or fails to locate files from the search string in the lpFileName parameter, the return value is INVALID_HANDLE_VALUE and the contents of lpFindFileData are indeterminate. To get extended error information, call the GetLastError function.
If the function fails because no matching files can be found, the GetLastError function returns ERROR_FILE_NOT_FOUND.

5.FindNextFile Function

Continues a file search from a previous call to the FindFirstFile or FindFirstFileEx function.

Syntax

BOOL WINAPI FindNextFile(
  __in   HANDLE hFindFile,
  __out  LPWIN32_FIND_DATA lpFindFileData
);

Parameters

hFindFile [in]

The search handle returned by a previous call to the FindFirstFile or FindFirstFileEx function.

lpFindFileData [out]

A pointer to the WIN32_FIND_DATA structure that receives information about the found file or subdirectory. The structure can be used in subsequent calls to FindNextFile to indicate from which file to continue the search.

Return Value

If the function succeeds, the return value is nonzero and the lpFindFileData parameter contains information about the next file or directory found.
If the function fails, the return value is zero and the contents of lpFindFileData are indeterminate. To get extended error information, call the GetLastError function.
If the function fails because no more matching files can be found, the GetLastError function returns ERROR_NO_MORE_FILES.

6. GetProcAddress Function

Retrieves the address of an exported function or variable from the specified dynamic-link library (DLL).

Syntax

Copy

FARPROC WINAPI GetProcAddress(
  __in  HMODULE hModule,
  __in  LPCSTR lpProcName
);

Parameters

hModule [in]

A handle to the DLL module that contains the function or variable. The LoadLibrary, LoadLibraryEx, or GetModuleHandle function returns this handle. The GetProcAddress function does not retrieve addresses from modules that were loaded using the LOAD_LIBRARY_AS_DATAFILE flag. For more information, see LoadLibraryEx.

lpProcName [in]

The function or variable name, or 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 Value

If the function succeeds, the return value is the address of the exported function or variable.
If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

The spelling and case of a 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 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 Conventions for 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.
If the function might not exist in the DLL module—for example, if the function is available only on Windows Vista but the application might be running on Windows XP—specify the function by name rather than by ordinal value and design your application to handle the case when the function is not available, as shown in the following code fragment.