C + +: Determine if a folder exists (exist)

Write the program, you need to write data in the folder, if the folder does not exist, you can not write, at the program entrance needs to be judged;

Two solutions to Windows because they belong to the system layer.

Reference: Http://stackoverflow.com/questions/8233842/how-to-check-if-directory-exist-using-c-and-winapi
1. Getfileattributesa () function

DWORD d = getfileattributesa (const char* filename); #include <windows.h>
Windows system functions to determine whether a folder exists;

Code:

#include <iostream> #include <string> #include <windows.h> using namespace std;  
    BOOL Direxists (const std::string& dirname_in) {DWORD Ftyp = Getfileattributesa (Dirname_in.c_str ());  if (Ftyp = = invalid_file_attributes) return false;  
      
    Something is wrong with your path!   if (Ftyp & File_attribute_directory) return true;  
      
    This is a directory!    return false;  
This isn't a directory!  
      
    int main (void) {std::string folder ("./test");  
    if (direxists (folder) {std::cout << "folder:" << folder << "exist!" << Std::endl;  
    else {std::cout << "folder:" << folder << "doesn ' t exist!" << Std::endl;  
      
    } std::string Nofolder ("./testno"); if (direxists (Nofolder)) {std::cout << "folder: << nofolder <<" exist!"<< Std::endl;  
    else {std::cout << "folder:" << nofolder << "doesn ' t exist!" << Std::endl;  
return 0; }

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2. _access () function

int access (const char *filename, int mode); #include <io.h>

Mode is set to 0, to determine whether the file exists; Returns 0, the file exists;

Code:

#include <iostream> #include <string> #include <io.h> using namespace std;  
      
    BOOL Direxists (const std::string& dirname_in) {int Ftyp = _access (Dirname_in.c_str (), 0);   if (0 = Ftyp) return true;  
    This is a directory!    else return false;  
This isn't a directory!  
      
    int main (void) {std::string folder ("./test");  
    if (direxists (folder) {std::cout << "folder:" << folder << "exist!" << Std::endl;  
    else {std::cout << "folder:" << folder << "doesn ' t exist!" << Std::endl;  
      
    } std::string Nofolder ("./testno"); if (direxists (Nofolder)) {std::cout << "folder:" << nofolder << "exist!" << std::end  
    L else {std::cout << "folder:" << nofolder << "doesn ' t exist!" << std::endl  
return 0; }

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