Question

Write a C++ programm which

• reads an input file named 'input.txt'
• content of input.txt are not known to you
• copies content of input file into an output file named 'output.txt'
• contents of output.txt should be exactly the same as contents of input.txt
• the user should be given a choice to select input and output file in any folder
• remember to check that input file opened successfully

Please add comments next to the code, so I can learn from the solution. Also please use beginner coding, nothing too advance.

Answer 1

Below is the solution:

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
   fstream fRead,fWrite; //create a file stream to read and write a file
   char fname1[20], fname2[20]; //variable of input and output file name
   string line; //variable to read file line
   cout<<"Enter source file name with extension (input.txt) : "; //ask to enter file name to read
   gets(fname1); //file name from keyboard
   fRead.open(fname1); //open file to read
   if(!fRead) //if file is not found to read
   {
       cout<<"Error!! in opening file!"; //print the error
       exit(1); //exit
   }
   cout<<"Enter output file name with extension (output.txt) : "; //ask to enter file name to write
   gets(fname2); //file name from keyboard
   fWrite.open(fname2); //open a file to write
   if(!fWrite) //if file not found
   {
       cout<<"Error!! in opening file!";
       fRead.close(); //close file opened
       exit(2); //exit
   }
  
   while (getline(fRead, line) ) //loop until end of the file line by line
    {
       fWrite<<line<<endl; //write each line to the file
   }
   cout<<"File copied successfully..!!"; //message to file content written
   fRead.close(); //close the file
   fWrite.close(); //close the file
   return 0;
}

sample output:

Enter source file name with extension (input.txt) : input.txt
Enter output file name with extension (output.txt) : output.txt
File copied successfully..!!

Enter source file name with extension (input.txt) : input1.txt
Error!! in opening file!

input.txt:

This is a first line.
This is another line.
1 2 3 4 5

output.txt:

This is a first line.
This is another line.
1 2 3 4 5