sqaure.cppdouble square(double n){ return n * n;}main.cpp#include <iostream>#include <cstdlib>using namespace std;double square(double);int main(int argc, char *argv[]){ // Make sure the argument count is 2, otherwise display the help if (argc != 2){ cerr << "Usage: square <number>" << endl; return 1; } // String to double of Argument 1. double n = strtod(argv[1], 0); // Call the square method in square.cpp and display it on the screen. cout << "The square of " << argv[1] << " is " << square(n) << endl; return 0;}