C++17 ile Dosya Boyutu

file-size1.cpp

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream testFile("test.azw3", ios::binary);
    const auto begin = testFile.tellg();
    testFile.seekg (0, ios::end);
    const auto end = testFile.tellg();
    const auto fsize = (end-begin);

    cout << fsize << endl; // 38100108
}

file-size2.cpp

#include <iostream>
#include <filesystem>

namespace fs = std::filesystem;

int main()
{
    try {
        std::cout << fs::file_size("test.azw3") << std::endl;
    } catch(fs::filesystem_error& ex) {
        std::cout << ex.what() << '\n';
    }
}

file-size3.cpp

#include <iostream>
#include <filesystem>

namespace fs = std::filesystem;

int main()
{
    std::error_code ec{};
    auto size = fs::file_size("test.azw3", ec);
    if (ec == std::error_code{})
        std::cout << size << '\n';
    else
        std::cout << "error when accessing test file, size is: "
                  << size << " message: " << ec.message() << '\n';
}