File finder sample C++ code by Auax.

FileFinder.cpp

#include <iostream>
#include <string>
#include <chrono>
#include <filesystem>
#include <stdlib.h>

// set filesystem namespace
namespace fs = std::filesystem;

std::string getOsName()
{
#ifdef _WIN32
    return "Win-32";
#elif _WIN64
    return "Win-64";
#elif __APPLE__ || __MACH__
    return "MacOS";
#elif __linux__
    return "Linux";
#elif __FreeBSD__
    return "FreeBSD";
#elif __unix || __unix__
    return "Unix";
#else
    return "Other";
#endif
}

bool getEnvVarName(const char** const var) {
    std::string OS = getOsName();

    if (OS == "Win-32" || OS == "Win-64") *var = "USERPROFILE";
    else if (OS != "Other") *var = "HOME";
    else
    {
        return false;
    }
    return true;
}

int main()
{
    std::cout << "Enter the filename: ";
    std::string fileName;
    std::cin >> fileName;

    // get env var 
    const char* envName;
    bool isOtherOS;
    isOtherOS = getEnvVarName(&envName);

    // Exit in case of undefined envName and undefined OS.
    if (!isOtherOS) exit(1);

    // _dupenv_s
    char* buf = nullptr;
    size_t sz = 0;

    if (_dupenv_s(&buf, &sz, envName) == 0 && buf != nullptr)
    {
        // Start measuring time
        auto begin = std::chrono::high_resolution_clock::now();
        free(buf); // free buffer

        int nOfFiles = 0;
        std::string currentPath;

        for (const auto& entry : fs::recursive_directory_iterator(buf, std::filesystem::directory_options::skip_permission_denied)) {
            try { 
                std::string path = entry.path().string(); 
                std::string currentFile = path.substr(path.find_last_of("/\\") + 1);
                if (currentFile == fileName) {
                    currentPath = path;
                    break;
                }
            }
            catch (...) {
            }
            nOfFiles++;
        }
        
        std::cout << "Number of analyzed files: " << nOfFiles << "\n";
        std::cout << "File path: " << currentPath << "\n";
        
        auto end = std::chrono::high_resolution_clock::now();
        auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
        printf("Time: %.3f seconds.\n", elapsed.count() * 1e-9);

        system("pause");
    }
}