求strtok函数的实现代码.

[thorpe]

请大家帮忙回复一下strtok函数的实现代码.

[星羽]

vs2005的

char * __cdecl strtok (
        char * string,
        const char * control
        )
#endif  /* _SECURE_VERSION */
{
        unsigned char *str;
        const unsigned char *ctrl = control;

        unsigned char map[32];
        int count;

#ifdef _SECURE_VERSION

        /* validation section */
        _VALIDATE_RETURN(context != NULL, EINVAL, NULL);
        _VALIDATE_RETURN(string != NULL || *context != NULL, EINVAL, NULL);
        _VALIDATE_RETURN(control != NULL, EINVAL, NULL);

        /* no static storage is needed for the secure version */

#else  /* _SECURE_VERSION */

        _ptiddata ptd = _getptd();

#endif  /* _SECURE_VERSION */

        /* Clear control map */
        for (count = 0; count < 32; count++)
                map[count] = 0;

        /* Set bits in delimiter table */
        do {
                map[*ctrl >> 3] |= (1 << (*ctrl & 7));
        } while (*ctrl++);

        /* Initialize str */

        /* If string is NULL, set str to the saved
         * pointer (i.e., continue breaking tokens out of the string
         * from the last strtok call) */
        if (string)
                str = string;
        else
                str = _TOKEN;

        /* Find beginning of token (skip over leading delimiters). Note that
         * there is no token iff this loop sets str to point to the terminal
         * null (*str == '\0') */
        while ( (map[*str >> 3] & (1 << (*str & 7))) && *str )
                str++;

        string = str;

        /* Find the end of the token. If it is not the end of the string,
         * put a null there. */
        for ( ; *str ; str++ )
                if ( map[*str >> 3] & (1 << (*str & 7)) ) {
                        *str++ = '\0';
                        break;
                }

        /* Update nextoken (or the corresponding field in the per-thread data
         * structure */
        _TOKEN = str;

        /* Determine if a token has been found. */
        if ( string == str )
                return NULL;
        else
                return string;
}

[星羽]

另外一个版本

/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
#include <string.h>

char* strtok(char *s, const char *delim)
{
  const char *spanp;
  int c, sc;
  char *tok;
  static char *last;


  if (s == NULL && (s = last) == NULL)
    return (NULL);

  /*
   * Skip (span) leading delimiters (s += strspn(s, delim), sort of).
   */
 cont:
  c = *s++;
  for (spanp = delim; (sc = *spanp++) != 0;) {
    if (c == sc)
      goto cont;
  }

  if (c == 0) {                 /* no non-delimiter characters */
    last = NULL;
    return (NULL);
  }
  tok = s - 1;

  /*
   * Scan token (scan for delimiters: s += strcspn(s, delim), sort of).
   * Note that delim must have one NUL; we stop if we see that, too.
   */
  for (;;) {
    c = *s++;
    spanp = delim;
    do {
      if ((sc = *spanp++) == c) {
        if (c == 0)
          s = NULL;
        else
          s[-1] = 0;
        last = s;
        return (tok);
      }
    } while (sc != 0);
  }
  /* NOTREACHED */
}

[waizqfor]

char *strtok(register char *s,register const char *delim )
{
        register char *spanp;
        register int c, sc;
        char *tok;
        static char *last;


        if (s == NULL && (s = last) == NULL)
                return (NULL);
                
cont:
        c = *s++;
        for (spanp = (char *)delim; (sc = *spanp++) != 0 {
                if (c == sc)
                        goto cont;
        }

        if (c == 0) {
                last = NULL;
                return (NULL);
        }
        tok = s - 1;

        for (; {
                c = *s++;
                spanp = (char *)delim;
                do {
                        if ((sc = *spanp++) == c) {
                                if (c == 0)
                                        s = NULL;
                                else
                                        s[-1] = 0;
                                last = s;
                                return (tok);
                        }
                } while (sc != 0);
        }
}

[zjf30366]

strtok用来分解字符串，使用后会将字符串破坏掉。

[yanxiaotao]

char *strtok_func(char *strToken, const char *strDelimit)
{
static char *pToken = NULL;
char *pchDelimit = NULL;
char *pchRetToken = NULL;
char ucFlag = 0;

if (strToken != NULL)
{
pToken = strToken;
}

if ((*pToken == '\0') || (pToken == NULL))
{
return NULL;
}

pchRetToken = pToken;
while (*pToken != '\0')
{
for (pchDelimit = strDelimit; *pchDelimit != '\0'; pchDelimit ++)
{
if (*pchRetToken == *pchDelimit)
{
pchRetToken ++;
break;
}

if (*pToken == *pchDelimit)
{
*pToken = '\0';
ucFlag = 1;
}
}
pToken ++;

if (ucFlag == 1)
{
break;
}
}

return pchRetToken;
}