yhlleo / cFilenameAnalysis

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首先,看一下C/C++中的路径解析与合成的两个函数_splitpath_makepath

_CRT_INSECURE_DEPRECATE(_splitpath_s) _CRTIMP void   __cdecl _splitpath(_In_z_ const char * _FullPath, _Pre_maybenull_ _Post_z_ char * _Drive, _Pre_maybenull_ _Post_z_ char * _Dir, _Pre_maybenull_ _Post_z_ char * _Filename, _Pre_maybenull_ _Post_z_ char * _Ext);
  
void  __cdecl _makepath(char* _Path, const char* _Drive, const char* _Dir, const char* _Filename, const char* _Ext);

不要被复杂的函数声明给吓到,其实很简单。

对于_splitpath路径解析函数:

  • _FullPath: 全路径(input)
  • _Drive : 盘符(output)
  • _Dir: 除去盘符和文件名的中间路径(output)
  • _Filename:文件名(output)
  • _Ext:拓展名(output)

对于_makepath路径合成函数,上述的参数含义相同,只是输入与输出相反。

给出一段代码示例:

#include <stdlib.h>  
#include <stdio.h>  
  
void main( void )  
{  
   char full_path[_MAX_PATH];  
   char drive[_MAX_DRIVE];  
   char dir[_MAX_DIR];  
   char fname[_MAX_FNAME];  
   char ext[_MAX_EXT];  
  
   _makepath( full_path, "c", "\\sample\\file\\", "makepath", "c" );  
   printf( "_FullPath created with _makepath: %s\n\n", full_path);  
   _splitpath( full_path, drive, dir, fname, ext );  
   printf( "Path extracted with _splitpath:\n" );  
   printf( "  _Drive: %s\n", drive );  
   printf( "  _Dir: %s\n", dir );  
   printf( "  _Filename: %s\n", fname );  
   printf( "  _Ext: %s\n", ext );  
}  
  
  
// Output  
  
_FullPath created with _makepath: c:\sample\file\makepath.c

Path extracted with _splitpath:
  _Drive: c:
  _Dir: \sample\file\
  _Filename: makepath
  _Ext: .c

其中的一些宏定义如下:

/*
 * Sizes for buffers used by the _makepath() and _splitpath() functions.
 * note that the sizes include space for 0-terminator
 */
#define _MAX_PATH   260 /* max. length of full pathname */
#define _MAX_DRIVE  3   /* max. length of drive component */
#define _MAX_DIR    256 /* max. length of path component */
#define _MAX_FNAME  256 /* max. length of file name component */
#define _MAX_EXT    256 /* max. length of extension component */

有时候,我们仅需要获得文件的文件名或者拓展名,那么用上述的方法就有点繁琐,string类型及其操作函数就能很方便地实现:

string filePath = "E:\\file\\main.cpp";

string extendName;
int iBeginIndex  = filePath.find_last_of(".")+1;
int iEndIndex    = filePath.length();
extendName       = filePath.substr( iBeginIndex, iEndIndex-iBeginIndex );
transform( extendName.begin(), extendName.end(), extendName.begin(), tolower ); 
cout << extendName << endl;

// Output : cpp

同理,如果想用该方法获取文件名,只需将filePath.find_last_of(".")修改为filePath.find_last_of("\\"),另外,这里为了使输出的文件拓展名一致,使用了transform函数,其中的参数tolower,含义是如果该字符有对应的小写字符,则转为小写字符。

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