How to check if a file exists before creating a new file

Question

I want to input some contents to a file, but I\'d like to check first if a file with the name I wish to create exists. If so, I don\'t want to create any file, even if the f

Answer 1

I just saw this test:

bool getFileExists(const TCHAR *file)
{ 
  return (GetFileAttributes(file) != 0xFFFFFFFF);
}

Answer 2

C++17, cross-platform: Using std::filesystem::exists and std::filesystem::is_regular_file.

#include <filesystem> // C++17
#include <fstream>
#include <iostream>
namespace fs = std::filesystem;

bool CreateFile(const fs::path& filePath, const std::string& content)
{
    try
    {
        if (fs::exists(filePath))
        {
            std::cout << filePath << " already exists.";
            return false;
        }
        if (!fs::is_regular_file(filePath))
        {
            std::cout << filePath << " is not a regular file.";
            return false;
        }
    }
    catch (std::exception& e)
    {
        std::cerr << __func__ << ": An error occurred: " << e.what();
        return false;
    }
    std::ofstream file(filePath);
    file << content;
    return true;
}
int main()
{
    if (CreateFile("path/to/the/file.ext", "Content of the file"))
    {
        // Your business logic.
    }
}

Answer 3

you can also use Boost.

 boost::filesystem::exists( filename );

it works for files and folders.

And you will have an implementation close to something ready for C++14 in which filesystem should be part of the STL (see here).