CODEWITHSUNDEEP
csplitc-stringsstrtokfunction-definition
Merrifield
Merrifield

Reputation: 23

Please tell me what's wrong with my strtok function

I created the strtok function as below. However, although I didn't get an error, it didn't work. Please tell me where the problem is. I'm sorry if this sentence is hard to read.

#include <stddef.h> // NULL
#include <stdlib.h> // calloc
#include <string.h> // strncpy

char* my_strtok(char *src, const char *delims) {

static char* nextgettok;
char *nxt;//トークンの先頭アドレス
char *dlm;//トークンの区切アドレス

if(*delims){
  nextgettok = src;
}else{
  src =nextgettok;
}

nxt = NULL;
while(*src)
{
  if(nxt == NULL)
  {
    if(strchr(src,*delims) == NULL)nxt = src;
  }else
  {
        if(strchr(src,*delims) != NULL)
        {
          dlm = src;
          *dlm = '\0';
          nextgettok = dlm + 1;
          break;
        }
   }
   src++;
}
  return nxt;

}

Upvotes: 0

Views: 71

Answers (1)

Vlad from Moscow
Vlad from Moscow

Reputation: 311018

This code snippet

if(*delims){
  nextgettok = src;
}else{
  src =nextgettok;
}

does not make a sense.

It seems you mean

if ( src ) nextgettok = src;

This while loop

while(*src)
{

can invoke undefined behavior in the case when the first argument is equal to NULL and according to the description of the function the first argument may be equal to NULL.

Also such a call of strchr as in these if statements

if(strchr(src,*delims) == NULL)nxt = src;

and

if(strchr(src,*delims) != NULL)

also does not make sense because the string pointed to by delims can contain more than one character.

Instead of the function strchr you should use the standard functions strspn and strcspn.

So the function definition in whole does not make a sense.

Please reread the description of the function strtok at least in the internet.

Upvotes: 1

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