Realization and application of strtok function

Turn from: http://blog.csdn.net/ast_224/article/details/3977311

Strtok
#include <string.h>
Char *strtok (char *str, const char *delim);
Char *strtok_r (char *str, const char *delim, char **saveptr);
Function: Explode a string into a set of tag strings. STR is the string to be decomposed, Delim as a delimiter string.
Note: At the first invocation, STR must point to the string to be decomposed, and then call to set S to null.
Strtok finds the characters contained in Delim in STR and replaces it with null ('/0 ') until the entire string is searched.
Returns a pointer to the next tag string. Returns the null character null when no string is marked.
Example: Use Strtok to determine whether an IP address is legitimate: ip_strtok.c:

[C-sharp]  View plain copy//ip_strtok.c   #include  <stdio.h>   #include  < string.h>   Int main (INT&NBSP;ARGC,&NBSP;CHAR&NBSP;**ARGV)    {       char temp_buf[100] = {};      char p_temp[100];       char *p=NULL;      char *t =  ".";       int m,n,i;      int j=0,s=0;             if (argc!=2)       {         printf ("param must 2/n");        return -1;       }      strcpy (temp_buf, argv[1]);       for (I=0; i<strlen (TEMP_BUF); i++)       {          if (temp_buf[i] == *t) j++;        if (temp_buf[i] = = *t &&  (temp_buf[i+1]>= ' 0 ' &&temp_buf[i+1]<= ' 9 '))          {          s++;         }      }      if (j!=3 | |  j!=s)       {        printf ("Ip param  format error/n ");        return -1;       }      p = strtok (temp_buf, t);             while (p!=null)       {          strcpy (p_temp, p);         printf ("%s /n",  p_temp);    &Nbsp;    for (N=0; n<strlen (p_temp); n++)           {           if ( p_temp[n]>= ' 0 ' &&p_temp[n]<= ' 9 ')            {              printf ("ip param error/n");              return -1;            }         }                   m = atoi (p_temp);          if (m>255)          {            printf ("ip invalid /n");           return -1;         }                   p=strtok (null,  ".");          printf ("p = %s/n", p);      }       printf ("OK