c++从文件路径获取目录

#include<iostream>
#include<string>
using namespace std;

int main()
{
    //string filePath = "D:\statistics_chengqichao\qcc\biaoxiandianyun.xyz";
    //int nPos = filePath.rfind('\');
    //string prefixPath = filePath.substr(0, filePath.length() - nPos-1);
    //cout << prefixPath << endl;





    string filename = "C:\MyDirectory\MyFile.txt";
    

    string directory;
    const size_t last_slash_idx = filename.rfind('\');
    if (std::string::npos != last_slash_idx)
    {
        directory = filename.substr(0, last_slash_idx);

    }
    cout << directory << endl;
    system("pause");
    return 0;
}