how to use fstream c++ code example

Example 1: fstream in c++

#include<fstream>
int main()
{
  fstream file; 
  /*if we use fstream then we need to specify at least one 
  parameter mode like ios::out or ios::in else the file will not open */  
  file.open("filename.txt", ios::out|ios::in);
  /*all work with file*/
  file.close();
  return 0;
}

Example 2: 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;