指针增量与 C 中的索引增量相比如何

Question

consider the following two code:

void PrintLetter(char *src)
{
 while(*src != '\0')
 {
   printf("%c",*src);
   src++;
 }
}

and

void PrintLetter(char *src)
{
 int i;
 for(i=0;src[i];i++)
  printf("%c",src[i]);
}

Is there any performance difference between the two?

Answer 1

None whatsoever. The compiler will perform its optimizations regardless of the form you are writing. The underlying assembly code is the same.

Answer 2

Any performance difference will depend on the compiler.

Some small embedded systems have quite simplistic compilers that may produce slightly different code for one than the other -- though without testing, it's hard to guess which might end up "better" (though if I had to guess "blindly", I'd probably pick the first).

With the compilers on typical desktop/server systems (eg, gcc, VC++, EDG) you're likely to get (essentially) identical results either way, so choosing between them is purely a matter of picking what you find more readable.