Comparison Efficiency

Question

What is generally faster:

if (num >= 10)

or:

if (!(num < 10))

Answer 1

The compiler will most likely optimize that sort of thing. Don't worry about it, just code for clarity in this case.

Assembly languages often have operations for >= and <= that are the same number of steps as < and >. For instance, with a Motorola 68k, if you want to compare the data registers %d0 and %d1 and branch if %d0 is greater than or equal to %d1, you would say something like:

cmp %d0, %d1  // compare %d0 and %d1, storing the result
              // in the condition code registers.
bge labelname // Branch to the given label name if the comparison
              // yielded "greater than or equal to" (hence bge)

It's a common mistake to think that a >= b means the computer will perform two operations instead of one because of that "or" in "greater than or equal to".