strtok对数组做了什么

dyte200

如下程序找到被字符','或'.'间隔的字符串。
[php]
#include<string.h>
main ()
{
  char aa[] = ",,ab,,cd,ef.,n.,.,";
  int i;
  char *bb;

  for (i = 0; i < sizeof (aa); i++)
    printf ("%d,", aa);
  printf ("\naa=%s\n\n", aa);

  bb = strtok (aa, ",.");
  for (i = 0; i < sizeof (aa); i++)
    printf ("%d,", aa);
  printf ("\naa=%s\n", aa);
  printf ("bb=%s\n\n", bb);

  while ((bb = strtok (NULL, ",.")) != NULL)
    {
      for (i = 0; i < sizeof (aa); i++)
        printf ("%d,", aa);
      printf ("\naa=%s\n", aa);
      printf ("bb=%s\n", bb);
    }
}
[/php]
结果显示：
44,44,97,98,44,44,99,100,44,101,102,46,44,110,46,44,46,44,0,
aa=,,ab,,cd,ef.,n.,.,

44,44,97,98,0,44,99,100,44,101,102,46,44,110,46,44,46,44,0,
aa=,,ab
bb=ab

44,44,97,98,0,44,99,100,0,101,102,46,44,110,46,44,46,44,0,
aa=,,ab
bb=cd
44,44,97,98,0,44,99,100,0,101,102,0,44,110,46,44,46,44,0,
aa=,,ab
bb=ef
44,44,97,98,0,44,99,100,0,101,102,0,44,110,0,44,46,44,0,
aa=,,ab
bb=n
说明strtok对原数组aa进行了更改：
1.开头的','或'.'不改。
2.如果遇到连续的',.'串，只将第一个改为'\0'。

MMMIX

strtok 本来就会对传入的字符数组进行修改, 一般介绍 ANSI C 标准库的书上都有提到.

在 Brian W. Kernighan and Rob Pike 的 The Practice of Programming 对次此有
专门的讨论