FStream读取txt文件

我尝试了很多解决方案，但都不起作用，无论是绝对路径还是相对路径。我也更改了目录等等。我的代码总是这样工作的，我不知道哪里出了问题。

我所做的两个例子：

// Read a file into memory
#include <iostream>     // std::cout
#include <fstream>      // std::ifstream
int main () {
    std::ifstream is ("test.txt", std::ifstream::binary);
    if (is) {
        // Get length of file:
        is.seekg (0, is.end);
        int length = is.tellg();
        is.seekg (0, is.beg);
        char * buffer = new char [length];
        std::cout << "Reading " << length << " characters... ";
        // Read data as a block:
        is.read (buffer,length);
        if (is)
           std::cout << "all characters read successfully.";
        else
           std::cout << "error: only " << is.gcount() << " could be read";
        is.close();
        // ...buffer contains the entire file...
        std::cout << buffer;
        system("PAUSE");
        delete[] buffer;
    }
    return 0;
}

和

char pfad[256]; //The path to the application is stored here.
_getcwd( pfad, 256);
std::string truepfad;
truepfad = pfad;
truepfad.append("\test.txt");
fstream f("C:\Users\Etix\Documents\test.txt");
string s;
if (!f)
    std::cout << truepfad;
else
{
    std::cout << "open file";
    while (getline(f, s)){
        std::cout << s;
    }
}