C++怎么操作二进制文件 C++二进制文件读写的方法详解

#include <iostream>
#include <fstream>

using namespace std;

struct MyData {
    int id;
    double value;
};

int main() {
    // 写入二进制文件
    MyData data1 = {1, 3.14};
    ofstream outfile("mydata.bin", ios::binary);
    if (outfile.is_open()) {
        outfile.write(reinterpret_cast<const char*>(&data1), sizeof(data1));
        outfile.close();
        cout << "Data written to file." << endl;
    } else {
        cerr << "Unable to open file for writing." << endl;
        return 1;
    }

    // 读取二进制文件
    MyData data2;
    ifstream infile("mydata.bin", ios::binary);
    if (infile.is_open()) {
        infile.read(reinterpret_cast<char*>(&data2), sizeof(data2));
        infile.close();
        cout << "Data read from file: id = " << data2.id << ", value = " << data2.value << endl;
    } else {
        cerr << "Unable to open file for reading." << endl;
        return 1;
    }

    return 0;
}

// 写入结构体数组
MyData dataArray[3] = {{1, 3.14}, {2, 2.71}, {3, 1.618}};
ofstream outfile("mydata_array.bin", ios::binary);
if (outfile.is_open()) {
    for (int i = 0; i < 3; ++i) {
        outfile.write(reinterpret_cast<const char*>(&dataArray[i]), sizeof(MyData));
    }
    outfile.close();
    cout << "Data array written to file." << endl;
}

// 读取结构体数组
MyData readArray[3];
ifstream infile("mydata_array.bin", ios::binary);
if (infile.is_open()) {
    for (int i = 0; i < 3; ++i) {
        infile.read(reinterpret_cast<char*>(&readArray[i]), sizeof(MyData));
        if (infile.eof()) break; // 避免读取到文件末尾后的错误
        cout << "Data read from file: id = " << readArray[i].id << ", value = " << readArray[i].value << endl;
    }
    infile.close();
}

// 写入字符串
string myString = "Hello, binary file!";
ofstream outfile("string.bin", ios::binary);
if (outfile.is_open()) {
    unsigned int length = myString.length();
    outfile.write(reinterpret_cast<const char*>(&length), sizeof(length));
    outfile.write(myString.c_str(), length);
    outfile.close();
    cout << "String written to file." << endl;
}

// 读取字符串
string readString;
ifstream infile("string.bin", ios::binary);
if (infile.is_open()) {
    unsigned int length;
    infile.read(reinterpret_cast<char*>(&length), sizeof(length));
    char* buffer = new char[length + 1]; // +1 for null terminator
    infile.read(buffer, length);
    buffer[length] = '\0'; // Null terminate the string
    readString = buffer;
    delete[] buffer;
    infile.close();
    cout << "String read from file: " << readString << endl;
}

#include <iostream>
#include <fstream>
#include <cstdint> // For uint32_t
#ifdef _WIN32
#include <winsock2.h> // For htonl, ntohl on Windows
#pragma comment(lib, "ws2_32.lib") // Link with winsock2 library
#else
#include <arpa/inet.h> // For htonl, ntohl on Linux/Unix
#endif

using namespace std;

// Function to check endianness
bool isLittleEndian() {
    uint32_t i = 0x01234567;
    // If the first byte is 0x67, then the system is little endian
    return (*((uint8_t*)&i)) == 0x67;
}


int main() {
    uint32_t value = 0x12345678;

    // Write to file in network byte order (big-endian)
    ofstream outfile("endian.bin", ios::binary);
    if (outfile.is_open()) {
        uint32_t networkValue = htonl(value); // Convert to network byte order
        outfile.write(reinterpret_cast<const char*>(&networkValue), sizeof(networkValue));
        outfile.close();
        cout << "Value written in network byte order." << endl;
    }

    // Read from file and convert back to host byte order
    uint32_t readValue;
    ifstream infile("endian.bin", ios::binary);
    if (infile.is_open()) {
        infile.read(reinterpret_cast<char*>(&readValue), sizeof(readValue));
        readValue = ntohl(readValue); // Convert back to host byte order
        infile.close();
        cout << "Value read in host byte order: 0x" << hex << readValue << dec << endl;
    }

    return 0;
}

#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

int main() {
    // 批量写入数据
    vector<int> data(1000000, 42); // 1 million integers
    ofstream outfile("large_data.bin", ios::binary);
    if (outfile.is_open()) {
        outfile.write(reinterpret_cast<const char*>(data.data()), data.size() * sizeof(int));
        outfile.close();
        cout << "Large data written to file." << endl;
    }

    // 批量读取数据
    vector<int> readData(1000000);
    ifstream infile("large_data.bin", ios::binary);
    if (infile.is_open()) {
        infile.read(reinterpret_cast<char*>(readData.data()), readData.size() * sizeof(int));
        infile.close();
        cout << "Large data read from file." << endl;
    }

    return 0;
}