C++文件读写常用操作

C++文件读写常用操作

最近的毕设工作要使用C++保存读取一些矩阵，此篇博文记录比较好用的C++文件读写操作。

写

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

using namespace std;

int main()
{

    float mat[3][3] = {{1,2,3}, {4,5,6}, {7,8,9}};

    string pic = "./output/mat.txt";

    // transfer string to char*
    char* pic_name = (char*)pic.data();

    ofstream fout;
    fout.open(pic_name);

    for (int i = 0; i < 3; ++i)
        for (int j = 0; j < 3; ++j)
            fout << mat[i][j] << " ";

    fout.close();

    return 0;
}

读

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

using namespace std;

int main()
{

    string path = "./output/mat.txt";
    char* pic_name = (char*)path.data();
    fstream in(pic_name);

    string line;
    while (getline(in, line))
    {
        double value;
        stringstream ss(line);

        // 按行读取
        while (ss >> value)
        {
            cout << value << endl;
        }

    }

    in.close();
    return 0;

}