就像从文件输入数据一样，可以将数据输出到文件。假设有一个矩阵，想把结果保存到一个文本文件中。可以看到，将矩阵输出到文件的代码和将矩阵输出到终端的代码非常相似。
#include <iostream>
#include <fstream>
#include <vector>using namespace std;int main() {// create the vector that will be outputtedvector < vector <int> > matrix (5, vector <int> (3, 2));vector<int> row;// open a file for outputting the matrixofstream outputfile;outputfile.open ("matrixoutput.txt");// output the matrix to the fileif (outputfile.is_open()) {for (int row = 0; row < matrix.size(); row++) {for (int column = 0; column < matrix[row].size(); column++) {if (column != matrix[row].size() - 1) {outputfile << matrix[row][column] << ", ";}else {outputfile << matrix[row][column];}}outputfile << endl; }}outputfile.close();return 0;
}