即使文件在同一目录中，ifstream 也找不到文件

Question

I've got a method to read a vector of bools from a file:

std::vector<bool> OPCConnector::getAlarmVector() {
    std::vector<bool> data;
    std::ifstream DataFile(filepath);

    if (DataFile) {
        bool value;

        while (DataFile >> value) {
            data.push_back(value);
            std::cout << value;
        }
    }
    
    return data;
}

The filepath variable is an object property that is assigned through the constructor:

OPCConnector::OPCConnector(std::string fpth) {
    filepath = fpth;
}

And in the main() function, the constructor is called:

std::vector<bool> activations;
std::string filepath = "alarmes.txt";
OPCConnector opcc = OPCConnector(filepath);
activations = opcc.getAlarmVector();

Now, I've checked what the folder of the executable is via GetModuleFileNameA() , and I made sure that the file is in the same directory and has the same name (also, I made sure that the extension isn't part of the file name, like "alarmes.txt.txt" ).

I debugged the first method getAlarmVector() and it never gets past the if (DataFile) condition, as if it won't find file.

I run the code using Visual Studio 2019, and nothing happens. The vector remains empty. Error is No such file or directory.

Default working directory is $(ProjectDir) and it's exactly where my file is.

Edit: I've also tried using both relative and absolute paths, none work.

Edit 2: I've also checked the directory using GetCurrentDirectory() and copied the .txt file there too, and it isn't working.

SOLUTION: Strangely enough, I deleted the file and created it again with the same name, and it worked. Thanks for the answers.

Answer 1

My guess: your current working directory isn't what you think it is, especially if you're running from an IDE. I know of several IDEs where the current working directory is some build directory (it varies by IDE) unless you specifically change it.

I'm fairly sure Visual Studio is one such IDE.

---

Here's a tiny example program I wrote;

$ g++ --std=c++17 Foo.cpp -o Foo && Foo
File opened.

Compile and run it:

 $ g++ --std=c++17 Foo.cpp -o Foo && Foo File opened.

Answer 2

Current folder and folder-of-exe-file are different things (sometimes). Try to specify full name of file (with disk, all folders, etc.).

You can check errors of file open operation by calling

if (!DataFile) { ... }

Answer 3

You can get an error code (and get a description of error in internet) if you use C-function fopen . If open is failed, you get the nullptr as result of fopen and errno will contain code of error.

Answer 4

The std::filesystem library can help you resolve file and path related issues.

#include <filesystem>


    // (in some function)
    std::filesystem::path filepath = "alarmes.txt";
    if ( !exists(filepath) )
    {
        std::cout << "File path " << filepath << " at absolute location "
                  << absolute(filepath) << " does not exist\n";
    }

See it on Compiler Explorer