File Content Copying in C++

Introduction

In this lab, we will learn how to copy contents of one file to another using file handling in C++ language.

Include Header Files and Namespaces

In the first step, we will include the necessary header files and namespaces in order to proceed with the code.

#include <iostream>
#include <fstream>

using namespace std;

Copy One File to Another

In this step, we will perform the following actions:

1. Create objects of ifstream and ofstream classes.
2. Check if they are connected to their respective files. If so, go ahead otherwise check the filenames twice. Read the contents of the source file using the getline() method and write the same to the destination using the << operator ( i.e. copy each line from ifstream object to ofstream object).
3. Close files after the copy using the close() method.

void copyFile(string sourceFile, string destinationFile){

    string line;

    // creating ifstream and ofstream objects
    ifstream sourceFileStream(sourceFile);
    ofstream destinationFileStream(destinationFile);

    // Reading from source file and writing to destination file
    if(sourceFileStream.is_open() && destinationFileStream.is_open()){
        while(getline(sourceFileStream, line)){
            destinationFileStream << line << "\n";
        }
        cout<<"Copy Finished"<<endl;
    }
    else{
        printf("Cannot read File");
    }

    //closing file
    sourceFileStream.close();
    destinationFileStream.close();
}

Main Function

In this step, we will create a main function to perform the file copy operation by calling our copyFile() function.

int main(){

    string sourceFile = "original.txt";
    string destinationFile = "copy.txt";

    copyFile(sourceFile, destinationFile);

    return 0;
}

Compile and Run

In this step,because the code file is saved in ~/project/main.cpp, we can change the current directory to ~/project and run the following commands in terminal:

g++ main.cpp -o main
./main

This will compile and execute the program and produces the output:

Copy Finished

Final Code

#include <iostream>
#include <fstream>

using namespace std;

void copyFile(string sourceFile, string destinationFile){

    string line;

    // creating ifstream and ofstream objects
    ifstream sourceFileStream(sourceFile);
    ofstream destinationFileStream(destinationFile);

    // Reading from source file and writing to destination file
    if(sourceFileStream.is_open() && destinationFileStream.is_open()){
        while(getline(sourceFileStream, line)){
            destinationFileStream << line << "\n";
        }
        cout<<"Copy Finished"<<endl;
    }
    else{
        printf("Cannot read File");
    }

    //closing file
    sourceFileStream.close();
    destinationFileStream.close();
}

int main(){

    string sourceFile = "original.txt";
    string destinationFile = "copy.txt";

    copyFile(sourceFile, destinationFile);

    return 0;
}

Summary

In this lab, an application was created that allows users to copy contents of one file to another file using file handling methods in C++ language.