#include <fstream>
#include <string>

int main() {
    // 創(chuàng)建輸出流（默認(rèn)覆蓋模式）
    std::ofstream outFile("data.txt");
    
    if (!outFile) {
        std::cerr << "文件創(chuàng)建失??！" << std::endl;
        return 1;
    }
    
    // 寫(xiě)入不同類(lèi)型數(shù)據(jù)
    outFile << "用戶日志\n";
    outFile << "ID: " << 1001 << "\n";
    outFile << "余額: $" << 2450.75 << "\n";
    
    // 自動(dòng)關(guān)閉文件（RAII）
    return 0;
}

#include <fstream>
#include <iostream>

int main() {
    std::ifstream inFile("data.txt");
    
    if (!inFile.is_open()) {
        std::cerr << "文件打開(kāi)失?。? << std::endl;
        return 1;
    }
    
    // 逐行讀取
    std::string line;
    while (std::getline(inFile, line)) {
        std::cout << line << std::endl;
    }
    
    // 重置讀取位置
    inFile.clear();
    inFile.seekg(0);
    
    // 格式化讀取
    int id;
    double balance;
    inFile.ignore(100, ':');  // 跳過(guò)"ID: "
    inFile >> id;
    inFile.ignore(100, '$'); // 跳過(guò)"余額: $"
    inFile >> balance;
    
    std::cout << "\n解析結(jié)果: ID=" << id 
              << ", 余額=" << balance << std::endl;
    
    return 0;
}

#include <fstream>

struct UserData {
    int id;
    double balance;
    char name[32];
};

int main() {
    UserData user = {1001, 2450.75, "張三"};
    
    std::ofstream binFile("user.dat", std::ios::binary);
    binFile.write(reinterpret_cast<char*>(&user), sizeof(user));
    
    return 0;
}

#include <fstream>
#include <iostream>

int main() {
    std::ifstream binFile("user.dat", std::ios::binary);
    
    if (!binFile) {
        std::cerr << "二進(jìn)制文件打開(kāi)失敗！" << std::endl;
        return 1;
    }
    
    UserData user;
    binFile.read(reinterpret_cast<char*>(&user), sizeof(user));
    
    std::cout << "用戶ID: " << user.id << "\n"
              << "姓名: " << user.name << "\n"
              << "余額: " << user.balance << std::endl;
    
    return 0;
}

// 示例：以追加模式寫(xiě)入文本
std::ofstream logFile("app.log", 
                     std::ios::out | std::ios::app);
                     
// 示例：讀寫(xiě)二進(jìn)制文件（不截?cái)啵?
std::fstream dataFile("records.dat",
                     std::ios::binary |
                     std::ios::in | 
                     std::ios::out);

std::fstream file("critical.dat");

// 檢查文件狀態(tài)
if (file.fail()) {
    std::cerr << "文件操作失敗！" << std::endl;
}

// 詳細(xì)錯(cuò)誤診斷
if (!file) {
    if (file.bad()) {
        std::cerr << "不可恢復(fù)的錯(cuò)誤" << std::endl;
    } else if (file.eof()) {
        std::cerr << "到達(dá)文件末尾" << std::endl;
    } else if (file.fail()) {
        std::cerr << "非致命錯(cuò)誤（如格式錯(cuò)誤）" << std::endl;
    }
}

{
    std::ofstream tmpFile("temp.txt");
    // 文件在作用域結(jié)束時(shí)自動(dòng)關(guān)閉
}

bool copyFile(const std::string& src, const std::string& dst) {
    std::ifstream in(src, std::ios::binary);
    std::ofstream out(dst, std::ios::binary);
    
    if (!in || !out) return false;
    
    const size_t BUFFER_SIZE = 4096;
    char buffer[BUFFER_SIZE];
    
    while (in.read(buffer, BUFFER_SIZE)) {
        out.write(buffer, BUFFER_SIZE);
    }
    out.write(buffer, in.gcount());  // 寫(xiě)入剩余字節(jié)
    
    return true;
}

#include <filesystem>
namespace fs = std::filesystem;

// 檢查文件存在
if (fs::exists("data.txt")) {
    // 獲取文件大小
    auto size = fs::file_size("data.txt");
    // 重命名文件
    fs::rename("old.txt", "new.txt");
}

class Logger {
public:
    Logger(const std::string& filename) 
        : logFile(filename, std::ios::app) {}
    
    ~Logger() { if (logFile) logFile.close(); }
    
    void log(const std::string& message) {
        if (!logFile) return;
        
        auto now = std::chrono::system_clock::now();
        auto time = std::chrono::system_clock::to_time_t(now);
        logFile << std::put_time(std::localtime(&time), "%F %T")
                << " | " << message << "\n";
    }
    
private:
    std::ofstream logFile;
};

// 使用示例
Logger logger("app.log");
logger.log("系統(tǒng)啟動(dòng)");
logger.log("用戶登錄: ID=1001");