IO流c++

IO流类库

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输入输出流

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#include <iostream>
using namespace std;class InCount
{
public:InCount(int a = 0, int b = 0){c1 = a;c2 = b;}void show(void){cout << "c1=" << c1 << "\t" << "c2=" << c2 << endl;}friend istream& operator>>(istream&, InCount&);friend ostream& operator<<(ostream&, InCount&);private:int c1, c2;
};istream& operator>>(istream& is, InCount& cc)
{is >> cc.c1 >> cc.c2;return is;
}ostream& operator<<(ostream& os, InCount& cc)
{os << "c1=" << cc.c1 << "\t" << "c2=" << cc.c2 << endl;return os;
}int main()
{InCount obj1, obj2;cout << obj1 << obj2 << endl; // 调用输出函数cin >> obj1;cin >> obj2;cout << obj1 << obj2;return 0;
}

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#include<iostream>
using namespace std;
#include<fstream>
int main()
{string s = "https://www.baidu.com";fstream fs;fs.open("file.txt", ios::out);fs.write(s.c_str(), s.size());fs.close();return 0;
}

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具体使用

#include <iostream>
#include <fstream>
using namespace std;int main()
{//ifstream inFile;//inFile.open(".\\demo.txt", ios::in);//if (inFile) // 条件成立，则说明文件打开成功//{//    cout << "\ndemo.txt文件打开成功." << endl;//    inFile.close();//}//else//{//    cout << "\ndemo.txt文件打开失败." << endl;//    return 1;//}//ofstream outFile;//outFile.open(".\\outdemo.txt", ios::out);//if (outFile) // 条件成立，则说明文件打开成功//{//    cout << "\noutdemo.txt文件打开成功." << endl;//    outFile.close();//}//else//{//    cout << "\noutdemo.txt文件打开失败." << endl;//}fstream ioFile;ioFile.open(".\\iodemo.txt", ios::in | ios::out | ios::trunc);if (ioFile){cout << "\niodemo.txt文件打开成功." << endl;ioFile.close();}else{cout << "\niodemo.txt文件打开失败." << endl;}return 0;
}

#include <iostream>
#include <fstream>
using namespace std;class student
{
public:int no;char name[10];int age;
};int main()
{student stu;ofstream outFile("student.dat", ios::out | ios::binary);if (!outFile){cout << "\n打开文件student.txt失败." << endl;outFile.close();}else{cout << "\n打开文件student.txt成功." << endl;}while (cin >> stu.no >> stu.name >> stu.age)outFile.write((char*)&stu, sizeof(stu));outFile.close();return 0;
}#include <iostream>
#include <fstream>
using namespace std;class student
{
public:int no;char name[10];int age;
};int main()
{student stu;ifstream inFile("student.dat", ios::in | ios::binary); // 二进制读方式打开此文件 if (!inFile){cout << "\n打开失败." << endl;return 0;}elsecout << "\nstudent.dat文件打开成功." << endl;while (inFile.read((char*)&stu, sizeof(stu))){cout << stu.no << "," << stu.name << "," << stu.age << endl;}inFile.close();return 0;
}

例子

#include <iostream>
#include <fstream>
using namespace std;int main()
{char ch;ofstream outFile("outdemo.txt", ios::out | ios::binary);if (!outFile){cout << "\noutdemo.txt文件打开失败." << endl;return 0;}elsecout << "\noutdemo.txt文件打开成功." << endl;while (cin >> ch){outFile.put(ch);}outFile.close();return 0;
}

例子

// 009.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//#include <iostream>
#include <fstream>
using namespace std;int main()
{char ch;ifstream inFile("outdemo.txt", ios::out | ios::binary);if (!inFile){cout << "\noutdemo.txt文件打开失败." << endl;return 0;}elsecout << "\noutdemo.txt文件打开成功." << endl;while ((ch=inFile.get())&& ch!=EOF){cout << ch;}inFile.close();return 0;
}