strtok and strcpy error

Question

I used strtok to split a string.

[UPDATE] I used your comments and answer for the new version below, but didn't work atm

int Crawl :: splitUrl(char ***tmp, int max_length, char *url)
{
 int idx=0;
 char * p;
 int i;

 p = strtok (url,"/");
 while (p != NULL && idx < max_length)
  {

   for (i=0;i<maxUrlSize-1 && p[i] != '\0';i++)
    (*tmp)[idx][i] = p[i];
   for ( ; i< maxUrlSize-1;i++)
    (*tmp)[idx][i] = '\0';

   printf("tmp[idx[%d]] %s\n",idx,(*tmp)[idx]);

   idx++;
   p = strtok (NULL, "/");
  }

 return idx;
};

The printf("tmp[idx] ... is correctly printed.

But in my main after I run the method:

  split_url = new char * [ maxUrlSplits ];
  for (int k=0;k<maxUrlSplits;k++)
   split_url[k] = new char [maxUrlSize];

  arr_size = crawl->splitUrl(&split_url,maxUrlSplits,url);

the array split_url is empty.

Compiler and gdb are fine.

Does someone have an idea?

how do you know the array is empty? I can run it without any problem. The array split_url is not empty. — Eric Z, May 01 '11 at 08:42
A bit OT but this is obviously C++, so why use arrays in the first place? — manneorama, May 01 '11 at 11:03
Please don't put status updates like [UPDATE] or [SOLVED] in your question titles - a clear summary of the question is all that's needed. Don't worry, everyone can see when you've updated your question. — razlebe, May 11 '11 at 11:14

score 1 · Answer 1 · answered May 01 '11 at 08:55

1

Seeing as you are not changing where the pointer is pointing, you only need to pass in a char * to your function. So

int Crawl :: splitUrl(char *tmp, int max_length, char *url)

answered May 01 '11 at 08:55

ColWhi

1,077
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16

score 0 · Answer 2 · answered May 01 '11 at 08:50

0

for (i=0;i<maxUrlSize || p[i] != '\0';i++)
    tmp[idx][i] = p[i];

This for loop can't be correct. You copy bytes a long as either condition is true. I believe you should copy only when both are true.

answered May 01 '11 at 08:50

Bo Persson

90,663
31
146
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user411313 · Answer 3 · 2011-05-01T08:54:36.850

Yes, this is correct. Every Parameter in C works as call by value, if you need a modification (fill your array), you should use a pointer.

       int Crawl :: splitUrl(char ***tmp, int max_length, char *url)
        {
         int idx=0;
         char * p;
         int i;

         p = strtok (url,"/");
         while (p != NULL)
          {

           for (i=0;i<maxUrlSize || p[i] != '\0';i++)
            (*tmp)[idx][i] = p[i];
           for ( ; i< maxUrlSize-1;i++)
            (*tmp)[idx][i] = '\0';

           printf("tmp[idx] %s\n",(*tmp)[idx]);

           idx++;
           p = strtok (NULL, "/");
          }


         return idx;
        };

...
      arr_size = crawl->splitUrl(&split_url,maxUrlSplits,url);

dereferencing pointers like that is strictly ANSI C compliant, works ever but not for NULL like in example — user411313, May 01 '11 at 11:27

strtok and strcpy error

3 Answers3