C++ File handling: Copy contents from one text file to another

Last update on August 16 2025 12:57:43 (UTC/GMT +8 hours)

5. Copy Contents of One Text File to Another

Write a C++ program to copy the contents of one text file to another.

Sample Solution:

C Code:

#include <iostream>   // Including the input/output stream library
#include <fstream>    // Including the file stream library
#include <string>     // Including the string handling library

int main() {
  // Open the input file
  std::ifstream inputFile("test.txt");    // Opening the file named "test.txt" for reading
  // Create or overwrite the output file
  std::ofstream outputFile("test_copy.txt");  // Creating/overwriting the file named "test_copy.txt" for writing

  if (inputFile.is_open() && outputFile.is_open()) {  // Checking if both input and output files were successfully opened
    std::string line;  // Declaring a string variable to store each line of text

    while (std::getline(inputFile, line)) {  // Loop through each line in the input file
      // Write each line to the output file
      outputFile << line << "\n";  // Writing each line to the output file with a newline character
    }

    inputFile.close();   // Closing the input file after copying
    outputFile.close();  // Closing the output file after copying

    std::cout << "File copied successfully." << std::endl;  // Displaying success message
  } else {
    std::cout << "Failed to open the files." << std::endl;  // Display an error message if file opening failed
  }

  return 0;  // Return 0 to indicate successful execution
}

Sample Output:

File copied successfully

Explanation:

In the above exercise,

Use the std::ifstream class to open the input file and the std::ofstream class to create or overwrite the output file.
Check if both files were successfully opened using the is_open() function.
If both files are open, use a while loop and std::getline() to read each line from the input file.
Write each line to the output file using the output stream operator <<.
After the loop ends, close both files using inputFile.close() and outputFile.close().
Finally, display a message indicating that the file was copied successfully

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to open a source file and copy its content to a destination file using file streams.
Write a C++ program that reads from one file and writes each line to a new file, ensuring that the copy is exact.
Write a C++ program to implement file copying by reading the source file character by character and writing to the target file.
Write a C++ program to copy a text file to another file and confirm the copy by comparing the file sizes.

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