c:math:abs

C++ Reference

abs

Syntax:

    #include <cstdlib>
    int abs( int num );

The abs() function returns the absolute value of num. For example:

     int magic_number = 10;
     cout << "Enter a guess: ";
     cin >> x;
     cout << "Your guess was " << abs( magic_number - x ) << " away from the
  magic number." << endl;