while（n> 0）和while（n！= 0）的评估之间的差异

Question

Is the evaluation of while(n>0) and while(n!=0) different? Basically both are to exit in the same condition. So is there a scenario when one of them should be used? Or will it make a difference in the performance efficiency by changing the loop condition when the number of times the loop being evaluated being the same?

Answer 1

This depends on your platform, but in general, it will perform identically. For example, for x86 architecture cmp operator will be used for both > or != . Here you can read more.

Answer 2

除了条件不同之外，性能没有明显区别。

Answer 3

In general, the difference will be neutral.

Anyway, one could maliciously think of special schemes like

while (n > 0)
{
  ...
  n++;
}

vs.

while (n != 0)
{
  ...
  n++;
}

where the compiler can infer that in the first snippet the test needs to be done on the first iteration only, and unroll the while into an if .