Which costs more while looping; assignment or an if-statement?

Question

Consider the following 2 scenarios:

boolean b = false;
int i = 0;
while(i++ < 5) {
    b = true;
}

OR

boolean b = false;         


        

Answer 1

Have you tested this? Working on a Linux system, I put your first example in a file called LoopTestNoIf.java and your second in a file called LoopTestWithIf.java, wrapped a main function and class around each of them, compiled, and then ran with this bash script:

#!/bin/bash
function run_test {
  iter=0
  while [ $iter -lt 100 ]
  do
    java $1
    let iter=iter+1
  done
}
time run_test LoopTestNoIf
time run_test LoopTestWithIf

The results were:

real    0m10.358s 
user    0m4.349s 
sys     0m1.159s 

real    0m10.339s
user    0m4.299s 
sys     0m1.178s

Showing that having the if makes it slight faster on my system.