c++中如何读写二进制文件_c++二进制文件I/O操作示例

#include <fstream>
#include <iostream>

int main() {
    std::ofstream file("data.bin", std::ios::out | std::ios::binary);
    if (!file) {
        std::cerr << "无法打开文件！" << std::endl;
        return 1;
    }

    int arr[] = {10, 20, 30, 40, 50};
    int size = sizeof(arr) / sizeof(arr[0]);

    file.write(reinterpret_cast<const char*>(arr), sizeof(arr));
    file.close();

    std::cout << "数据已写入 data.bin" << std::endl;
    return 0;
}

#include <fstream>
#include <iostream>

int main() {
    std::ifstream file("data.bin", std::ios::in | std::ios::binary);
    if (!file) {
        std::cerr << "无法打开文件！" << std::endl;
        return 1;
    }

    int arr[5];
    file.read(reinterpret_cast<char*>(arr), sizeof(arr));

    if (file.gcount() != sizeof(arr)) {
        std::cerr << "读取数据不完整！" << std::endl;
    } else {
        std::cout << "读取的数据：";
        for (int i = 0; i < 5; ++i) {
            std::cout << arr[i] << " ";
        }
        std::cout << std::endl;
    }

    file.close();
    return 0;
}

#include <fstream>
#include <iostream>
#include <string>

struct Student {
    int id;
    char name[20];
    float score;
};

int main() {
    // 写入结构体
    std::ofstream out("student.bin", std::ios::out | std::ios::binary);
    Student s1 = {1001, "Alice", 95.5f};
    out.write(reinterpret_cast<const char*>(&s1), sizeof(s1));
    out.close();

    // 读取结构体
    std::ifstream in("student.bin", std::ios::in | std::ios::binary);
    Student s2;
    in.read(reinterpret_cast<char*>(&s2), sizeof(s2));
    in.close();

    std::cout << "ID: " << s2.id << ", 姓名: " << s2.name 
              << ", 成绩: " << s2.score << std::endl;

    return 0;
}