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Jul 6th, 2009

get the rest of the string after a strtok

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If I simply just want to tokenize the first element of a string and then output the remainder of the string, how can this be accomplished?

thanks

c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
int main(){
  const char* line= "0 firstline";
  char* l = strdup(line);
  printf("beforeToknization:\t%s\n",l);
  char *tok = strtok(l," ");
  printf("firstToken:%s\trestOfLine:%s\n",tok,l);
  return 0;
}
#include <stdio.h>
#include <string.h>

int main(){
  const char* line= "0 firstline";
  char* l = strdup(line);
  printf("beforeToknization:\t%s\n",l);
  char *tok = strtok(l," ");
  printf("firstToken:%s\trestOfLine:%s\n",tok,l);
  return 0;
}

C Syntax (Toggle Plain Text)
./a.out
beforeToknization:      0 firstline
firstToken:0    restOfLine:0
./a.out
beforeToknization:      0 firstline
firstToken:0    restOfLine:0

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monkey_king

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Jul 6th, 2009

Re: get the rest of the string after a strtok

I don't know very much C programming but I am pretty good at google. http://www.elook.org/programming/c/strtok.html

BestJewSinceJC

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Jul 7th, 2009

Re: get the rest of the string after a strtok

Click to Expand / Collapse Quote originally posted by BestJewSinceJC ...

I don't know very much C programming but I am pretty good at google. http://www.elook.org/programming/c/strtok.html

I'm aware of the fact that I can tokenize the entire string,
but if I (dependent on the first token) just want the rest of the line,
without the need to tokenize it. How do I do that

monkey_king

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Jul 7th, 2009

Re: get the rest of the string after a strtok

You can use strchr function with space as the delimiter to mark the boundary of the first token and then read it accordingly.

Last edited by csurfer; Jul 7th, 2009 at 12:19 am.

csurfer

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Jul 7th, 2009

Re: get the rest of the string after a strtok

Click to Expand / Collapse Quote originally posted by csurfer ...

You can use strchr function with space as the delimiter to mark the boundary of the first token and then read it accordingly.

Ahh, cheers
Thanks!
This will come in handy

monkey_king

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Jul 7th, 2009

Re: get the rest of the string after a strtok

All strtok does is replace the delimiter with '\0'. If you skip over it, you'll find the rest of the string:

c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <string.h>
 
int main()
{
    char s[] = "a|b|c|d|e|f|g";
    char *tok = strtok(s, "|");
 
    printf("%s\n%s\n", tok, tok + strlen(tok) + 1);
 
    return 0;
}
#include <stdio.h>
#include <string.h>

int main()
{
    char s[] = "a|b|c|d|e|f|g";
    char *tok = strtok(s, "|");

    printf("%s\n%s\n", tok, tok + strlen(tok) + 1);

    return 0;
}

The only problem is there is no way to tell if strtok is finished until it returns NULL, and by then it's too late. If you know that there is more than one token, this works, but if not, you have to use something other than strtok to get the first token or do some extra testing:

c Syntax (Toggle Plain Text)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int main()
{
    char s[1024];
    char *p;
 
    printf("Type a sentence: ");
    fflush(stdout);
 
    if (!fgets(s, 1024, stdin)) return EXIT_FAILURE;
    if (p = strchr(s, '\n')) *p = '\0';
 
    if (!strpbrk(s, " \t\r\v")) printf("%s\n", s);
    else
    {
        char *tok = strtok(s, " \t\r\v");
 
        printf("%s\n%s\n", tok, tok + strlen(tok) + 1);
    }
 
    return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    char s[1024];
    char *p;

    printf("Type a sentence: ");
    fflush(stdout);

    if (!fgets(s, 1024, stdin)) return EXIT_FAILURE;
    if (p = strchr(s, '\n')) *p = '\0';

    if (!strpbrk(s, " \t\r\v")) printf("%s\n", s);
    else
    {
        char *tok = strtok(s, " \t\r\v");

        printf("%s\n%s\n", tok, tok + strlen(tok) + 1);
    }

    return 0;
}

Tom Gunn

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Jul 7th, 2009

Re: get the rest of the string after a strtok

My mistake, monkey king.

BestJewSinceJC

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Jul 8th, 2009

Re: get the rest of the string after a strtok

Why would you give me bad reputation for admitting I made a mistake? That doesn't make very much sense.

BestJewSinceJC

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Jul 8th, 2009

Re: get the rest of the string after a strtok

Click to Expand / Collapse Quote originally posted by BestJewSinceJC ...

Why would you give me bad reputation

"i dont know but here's google" may be appropriate in some cases, but Monkey_King posted a decent question, included formatted code, described the output he wanted, and asked why wasnt it working exactly the way he anticipated.

And the answer is not so easy, because strtok() is a difficult function for inexperienced programmers to understand from just a basic description.

to post a snarky, unhelpful RTFM-style answer is totally appropriate for newbs or other lazy sods who just want someone to do their work for them. But Monkey_King, as evidenced by the clarity of his post and the effort he made prior to posting, is obviously not in that group.

there are plenty of unhelpful or inappropriate posts on these forums. But i found your Post #2 to be both unhelpful and inappropriate so i neg-repped it. tux4life, as it turns out, disagreed with me so he pos-repped it.

now measured by net gain, you have come out ahead, gaining even more more rep points than Tom Gunn, the one person to actually post a thoughtful and correct solution.

so be proud. you scored.

and for someone who "doesn't know, but can use google", you did a good job whining for your rep

.

Last edited by jephthah; Jul 8th, 2009 at 2:16 pm.

jephthah

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Jul 8th, 2009

Re: get the rest of the string after a strtok

Let's review:

I misread his question, then made a mistake. I then realized this mistake, admitted my mistake, and apologized to monkey king. I didn't whine for rep nor did I ask anyone for rep. I wanted to know why you would disapprove of someone admitting a mistake, or why you would even get involved.

Last edited by BestJewSinceJC; Jul 8th, 2009 at 2:46 pm.

BestJewSinceJC

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