建立文件输出

文件输出步骤总结：

1、建立输出流对象，并将输出流对象和输出文件名绑定：ofstream sss_out("sssout.txt");

2、向输出流输出元素，有两种方式，一种是直接输出：sss_out<<输出内容；

                                                          

// Fig. 14.3: fig14_03.cpp
// Create a sequential file.
#include <iostream>
#include <string>
#include <fstream> // contains file stream processing types
#include <cstdlib> // exit function prototype
using namespace std;

int main()
{
                
    ofstream sss_out("sssout.txt");// 建立输出流sss_out，并将输出流和文件sssout.txt绑定

    // exit program if unable to create file
    if (!sss_out) // overloaded ! operator
    {
        cerr << "File could not be opened" << endl;
        exit(EXIT_FAILURE);
    } // end if

    cout << "Enter the account, name, and balance." << endl
        << "Enter end-of-file to end input.
? ";

    int account; // the account number
    string name; // the account owner's name
    double balance; // the account balance

    // read account, name and balance from cin, then place in file
    while (cin >> account >> name >> balance)
    {
        sss_out << account << ' ' << name << ' ' << balance << endl;//向输出流输出元素
        cout << "? ";
    } // end while
} // end main

 另一种可以建立输出流迭代器进行输出： ostream_iterator<int> out(out_xls," sss ");//sss为每个元素输出后输出的内容，即间隔。

#include<iostream>
#include<fstream>
#include<iterator>
using namespace std;

int main() {
    ofstream out_xls("int.txt");
    //istream_iterator<int> in(cin);
    ostream_iterator<int> out(out_xls," sss ");
    int i;
    while (cin >> i) {
        *out++ = i;
    }

}