C++：判断文件夹(folder)是否存在(exist)

写入程序, 需要在文件夹中写入数据, 如果文件夹不存在, 则无法写入, 在程序入口需要判断;

由于属于系统层, Windows的两种解决方法.

参考: http://stackoverflow.com/questions/8233842/how-to-check-if-directory-exist-using-c-and-winapi
1. GetFileAttributesA()函数

DWORD d = GetFileAttributesA(const char* filename); #include <windows.h>
windows系统函数, 判断文件夹是否存在;

代码:

#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 is not 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()函数

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

mode设为0, 判断文件是否存在; 返回0, 文件存在;

代码:

#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 is not 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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