二进制文件的输入和输出

streamObject.write(const char* s, int size)

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

using namespace std;

int main()
{
    ofstream binaryio("city.dat", ios::binary);
    string city = "北京";

    binaryio.write(city.c_str(), sizeof(city));
    binaryio.close();

    cout << "二进制文件city.dat创建成功！" << endl;

    return 0;
}

reinterpret_cast<datatype*>(address)

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

using namespace std;

int main()
{
    ofstream binaryio("temp.dat", ios::binary);
    int value = 120;

    binaryio.write(reinterpret_cast<char*>(&value), sizeof(value));
    binaryio.close();

    cout << "二进制文件temp.dat创建成功！" << endl;

    return 0;
}

streamObject.read(const char* address, int size)

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

using namespace std;

int main()
{
    ifstream binaryio("city.dat", ios::binary);
    char s[10];

    binaryio.read(s,10);
    cout << "读入的字节数为：" << binaryio.gcount() << endl;
    s[binaryio.gcount()] = '\0';
    cout << s << endl;
    binaryio.close();

    return 0;
}

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

using namespace std;

int main()
{
    ifstream binaryio("temp.dat", ios::binary);
    int value;

    binaryio.read(reinterpret_cast<char*>(&value),sizeof(value));
    cout << "读入的字节数为：" << binaryio.gcount() << endl;
    cout << value << endl;
    binaryio.close();

    return 0;
}