//  boost Program Execution Monitor program  --------------------------------//
int add( int i, int j ) { return i+j; }

int cpp_main( int, char *[] )  // note the name!
{ 
    // two ways to detect and report the same error:
    if ( add(2,2) != 4 ) throw "Oops..."; // #1 throws on error

    return add(2,2) == 4 ? 0 : 1;         // #2 returns error directly
}