how to save a cin into a file C++ code example

Example 1: how to open an input file in c++

#include <fstream>

ifstream file_variable; //ifstream is for input from plain text files
file_variable.open("input.txt"); //open input.txt

file_variable.close(); //close the file stream
/*
Manually closing a stream is only necessary
if you want to re-use the same stream variable for a different
file, or want to switch from input to output on the same file.
*/
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//You can also use cin if you have tables like so:
while (cin >> name >> value)// you can also use the file stream instead of this
{
 cout << name << value << endl;
}
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//ifstream file_variable; //ifstream is for input from plain text files
ofstream out_file;
out_file.open("output.txt");

out_file << "Write this scentence in the file" << endl;

Example 2: file reading c++

int a, b;
    
ifstream bd; 
myfile.open("file.txt");

if (myfile.is_open())
	while (bd >> a >> b)
    	cout << a << b << endl;

else cout << "ERROR";