C++: Pseudocode

Thoughts:

On some systems, modulus random number generation won't give you a quite right probability spread, because computers think in base 2 instead of base 10. Google for "modulo bias". This may be too nitpicky, so it may not be worth considering. What you are doing will work fine most of the time unless you are trying to do crypto or something.

You're generating a number between 1-100, and only testing the first 7 values. The if block will fall off the end without setting <r> to anything. In a case like this, you can write more robust code using a switch-case statement:

srand( timer() );  // Don't forget to seed your random number generator at the beginning of your code.  Odd C gotcha there.
switch( rand()%100 + 1 )
{
case 1: r=HUMAN; break;
case 2: r=DWARF; break;
case 3: r=ELF; break;
case 4: r=GNOME; break;
case 5: r=HALFELF; break;
case 6: r=HALFORC; break;
case 7: r=HOBBIT; break;
default: printf( "Fell through switch statement. This should never happen, so there must be an error in the code.\n" ); exit(1);
}

In the above code, it will check through those 7 values, but if you have generated a random number that isn't handled by the code, it will be caught by the "default" statement, print an error, and exit. Instead of going on to do weird stuff elsewhere in the code where nothing is actually wrong, but since <r> hasn't been set.