Read / Write a Text File

How to read a text file using C++? Here is an example:

Let's create a text file "myTest.txt", and type the following lines:

This is a test file

This is the second line of the test file

Then let's write a C++ program to read this file:

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

int main () {
   string line;
   //using ifstream to input file stream from a text file
   ifstream myfile ("myTest.txt");
   
   if (myfile.is_open())
   {
		while (! myfile.eof() )
		{
			getline (myfile,line);
			cout << line << endl;
		}
		
		myfile.close();
   }
	else cout << "Can't open file"; 
	
	return 0;
}

To write strings to a text file, we can write a program like this:

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

int main () {

	//using ofstream to output strings to a text file
   ofstream myfile ("myTest.txt");

   if (myfile.is_open())
   {
   	myfile << "This is a test.\n";
   	myfile << "I am learning C++.\n";
   	myfile.close();
   }
   else cout << "Can't open file";

   return 0;
}

In the above two examples, we include Stream class "fstream" as a header file to both read and write from/to files. Then for reading (input) from a text file, we use "ifstream" , for writing (output) to a text file, we use "ofstream".

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