Implementation example of reading and writing ini files in c++ standard library

#ifndef INIFILE_H
#define INIFILE_H

#include <string>
#include <map>
#include <fstream>
#include <sstream>

class IniFile {
public:
    // Constructor, accept file name    IniFile(const std::string& filename);

    // Load the contents of the INI file    void load();

    // Save content to INI file    void save() const;

    // Get the key value of the specified section    std::string getValue(const std::string& section, const std::string& key, const std::string& defaultValue = "") const;

    // Set the key value of the specified section    void setValue(const std::string& section, const std::string& key, const std::string& value);

private:
    std::string filename;  // INI file name    std::map<std::string, std::map<std::string, std::string>> data;  // Store sections and key-value pairs};

#endif // INIFILE_H

#include ""
#include <iostream>
#include <stdexcept>
#include <algorithm>

// Constructor, accept file nameIniFile::IniFile(const std::string& filename) : filename(filename) {
    load();  // Load the file contents}

// Load the contents of the INI filevoid IniFile::load() {
    std::ifstream file(filename);
    if (!file.is_open()) {
        throw std::runtime_error("Could not open file: " + filename);
    }

    std::string line;
    std::string currentSection;

    while (std::getline(file, line)) {
        // Remove comments and empty lines        (std::remove_if((), (), [](unsigned char c) { return std::isspace(c); }), ());
        if (() || line[0] == ';') {
            continue;  // Skip empty lines and comment lines        }

        // Processing Section        if (line[0] == '[') {
            auto endPos = (']');
            if (endPos != std::string::npos) {
                currentSection = (1, endPos - 1);  // Get the section name            }
            continue;
        }

        // Process key-value pairs        auto delimiterPos = ('=');
        if (delimiterPos != std::string::npos) {
            std::string key = (0, delimiterPos);
            std::string value = (delimiterPos + 1);
            data[currentSection][key] = value;  // Store key-value pairs        }
    }

    ();
}

// Save content to INI filevoid IniFile::save() const {
    std::ofstream file(filename);
    if (!file.is_open()) {
        throw std::runtime_error("Could not open file: " + filename);
    }

    for (const auto& section : data) {
        file << "[" <<  << "]\n";  // Write section        for (const auto& kv : ) {
            file <<  << "=" <<  << "\n";  // Write key-value pairs        }
        file << "\n";  // Blank lines between sections    }

    ();
}

// Get the key value of the specified sectionstd::string IniFile::getValue(const std::string& section, const std::string& key, const std::string& defaultValue) const {
    auto sectionIt = (section);
    if (sectionIt != ()) {
        auto keyIt = sectionIt->(key);
        if (keyIt != sectionIt->()) {
            return keyIt->second;  // Return the found value        }
    }
    return defaultValue;  // Return to the default value}

// Set the key value of the specified sectionvoid IniFile::setValue(const std::string& section, const std::string& key, const std::string& value) {
    data[section][key] = value;  // Set value}

#include <iostream>
#include ""

int main() {
    try {
        // Create an IniFile object and load an INI file        IniFile ini("");

        // Get key value        std::string username = ("UserSettings", "Username", "defaultUser");
        std::cout << "Username: " << username << std::endl;

        // Set new key value        ("UserSettings", "Username", "newUser");

        // Save to INI file        ();
        std::cout << "New username saved!" << std::endl;

    } catch (const std::exception& e) {
        std::cerr << "Error: " << () << std::endl;
    }

    return 0;
}