C/C++ 中判断某一文件或目录是否存在

方法一：C++中比较简单的一种办法（使用文件流打开文件）复制代码 1 #include 2 #include 3 4 using namespace std; 5 6 #define FILENAME "*.dat" // 指定文件名 7 8 int main( void ) 9 {10 fstream _file;11 _file.open(FILENAME, ios::in);12 if(!_file)13 {14 cout<<FILENAME<<"没有被创建!"<<endl;15 }16 else17
{18 cout<<FILENAME<<"已经存在!"<<endl;19 }20 21 cin.get();22 return 0;23 }复制代码方法二：利用C语言库函数（_access）函数原型：　　int _access( const char *path, int mode ）函数参数：　　l path：文件路径　　l mode：读写属性返回值（MSDN）： Each of these functions returns 0 if the file has the given mode. The function
returns –1 if the named file does not exist or is not accessible in the given mode; in this case, errno is set as follows:EACCES Access denied: file’s permission setting does not allow specified access.ENOENT Filename or path not found.EINVAL Invalid parameter.函数功能（MSDN）：
When used with files, the _access function determines whether the specified file exists and can be accessed as specified by the value of mode（见下图表）. When used with directories, _access determines only whether the specified directory exists; in Windows NT,
all directories have read and write access.复制代码/* ACCESS.C: This example uses _access to check the * file named "ACCESS.C" to see if it exists and if * writing is allowed. */#include #include #include void main( void ){ /* Check for existence */ if( (_access(
"ACCESS.C", 0 )) != -1 ) { printf( "File ACCESS.C exists " ); /* Check for write permission */ if( (_access( "ACCESS.C", 2 )) != -1 ) printf( "File ACCESS.C has write permission " ); }}输出：>>File ACCESS.C exists.>>File ACCESS.C has write permission复制代码方法三：使用Windows
API函数FindFirstFile(...)　　(1) 检查某一文件是否存在：复制代码#include "windows.h"int main(int argc, char *argv[]){ WIN32_FIND_DATA FindFileData; HANDLE hFind; printf ("Target file is %s. ", argv[1]); hFind = FindFirstFile(argv[1], &FindFileData); if (hFind == INVALID_HANDLE_VALUE)
{ printf ("Invalid File Handle. Get Last Error reports %d ", GetLastError ()); } else { printf ("The first file found is %s ", FindFileData.cFileName); FindClose(hFind); } return 0;} 复制代码　　(2) 检查某一目录是否存在：复制代码// 目录是否存在的检查：BOOL CheckFolderExist(const string
&strPath){ 　　WIN32_FIND_DATA FindFileData; BOOL bValue = false; HANDLE hFind = FindFirstFile(strPath.c_str(), &FindFileData); if ((hFind != INVALID_HANDLE_VALUE) && (wfd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) { 　　bValue = TRUE; } FindClose(hFind); return
bValue;}复制代码方法四：使用boost库中filesystem类库的exists函数复制代码#include #include #include using namespace boost::filesystem; int GetFilePath(std::string &strFilePath){ string strPath; int nRes = 0; //指定路径 strPath = "C:\"; path full_path( initial_path() ); full_path = system_complete(
path(strPath, native ) ); //判断各级子目录是否存在，不存在则需要创建 if ( !exists( full_path ) ) { bool bRet = create_directories(full_path); if (false == bRet) { return -1; } } strFilePath = full_path.native_directory_string(); return 0;}