Hi,

Whenever a user types ./a.out with the wrong number of arguments I want my program to output something like
Usage: ./a.out <-e/-d> <FIlename> <Value>

how can I do this?

You'll have to look at the arguments that main accepts:

int main( int argc, const char* argv[] )
{
    if (argc != 4)// program name and 3 arguments
    {
        std::cout << "Usage: ./a.out <-e/-d> <FIlename> <Value>\n";
        return 0;
    }
    //rest of the program
    return 0;
}

If you want to learn how/why this works, you should read this

commented: yes +17