#include <iostream> using namespace std; extern "C" long absolute_value(long x); long absolute_value(long x) { if (x<0) // if x is negative x = -x; // negate x return x; // return x } int main() { long theValue=0; cout << "Enter a value: " << endl; cin >> theValue; long theResult = absolute_value(theValue); cout << "The result is: " << theResult << endl; return 0; }