Clear Output Screen from C program
I'm not sure I entirely follow you, however; if you are using X-Code to compile and run C programs, output (e.g. any printf statements) should automatically be sent to the console, like so:

int main(int argc, const char * argv[])
{
   printf("Test program\n");
   getchar();
   return 0;
}


Is this the 'screen' you want to clear? If so, simply building and running any program which has no console output will do so (although I'd be interested to know why you need this.)

In the example above, comment out the line with the printf statement and build and run. You'll get a clear console.