C++ Program to Copy the Contents of One File Into Another File

Here, we will see how to develop a C++ program to copy the contents of one file into another file. Given a text file, extract contents from it and copy the contents into another new file. After this, display the contents of the new file.

Approach:

1. Open the first file which contains data. For example, a file named “file1.txt” contains three strings on three separate lines “Programming   Tutorials”, “By Geeks for geeks” and “Happy Coding!”. 
2. Open the second file to copy the data from the first file.
3. Extract the contents of the first file line by line and write the same content to the second file named “file2.txt” via while loop.
4. Extract the contents of the second file and display it via the while loop.

C++

// C++ to demonstrate copying
// the contents of one file
// into another file
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // filestream variables
    fstream f1;
    fstream f2;

    string ch;

    // opening first file to read the content
    f1.open("file1.txt", ios::in);

    // opening second file to write
    // the content copied from
    // first file
    f2.open("file2.txt", ios::out);

    while (!f1.eof()) {

        // extracting the content of
        // first file line by line
        getline(f1, ch);

        // writing content to second
        // file line by line
        f2 << ch << endl;
    }

    // closing the files
    f1.close();
    f2.close();

    // opening second file to read the content
    f2.open("file2.txt", ios::in);
    while (!f2.eof()) {
        // extracting the content of
        // second file line by
        // line
        getline(f2, ch);

        // displaying content
        cout << ch << endl;
    }

    // closing file
    f2.close();

    return 0;
}

Output:

Programming Tutorials
By Geeks for geeks
Happy Coding!