Thread: Don't quite understand how to use strtok()

So I want to loop through a file line by line. Everytime there is a ':' in a line, put the string before it into label. (i know that right now label keeps getting reset without ever doing anything with it)

Code:

int search(FILE *inp) {  
  char line[80];
  char label[11];
  char *tokenPtr;
  char delim1 = ':';
  int lineNum = 1;
  int i = 0;

  while(fgets(line, sizeof line, inp) != NULL) {  //loop through each line
    for(i = 0; i < 11; i++)
        label[i] = '\0';
    if (line[0] != '#' && line[0] != ' ') {  //if line doesnt start with # or a space...
      tokenPtr = strtok(line, delim1);   //split at :

//HOW DO I TAKE EVERYTHING BEFORE THE : AND ASSIGN IT TO label?
      //label = stdrup(tokenPtr);
        printf("%s\n", label);
      }
    }
    else if(line[0] == '\n') {
    continue;    //dont increase line number
    }
    lineNum++;
  }
return 0;
}

Take another look at the strtok function. I believe you have to use it twice to make it work the way you want. There should be shown an example in a decent book on 'C' in the 'String and Character Functions' chapter.

Your use of strtok looks fine to me. label is a char array, so it already has memory allocated for it, thus strdup is wrong. You only need to copy into it, so use strcpy.

Also, instead of using

Code:

for(i = 0; i < 11; i++)
    label[i] = '\0';

to clear the contents of label, do

Code:

memset(label, '\0', sizeof(label));

Actually, I take it back. You do have a problem with strtok. You're passing it delim1, which is a char. strtok requires a char * (a string) for delimiters, so declare

Code:

char *delim1 = ":";

Originally Posted by anduril462

Actually, I take it back. You do have a problem with strtok. You're passing it delim1, which is a char. strtok requires a char * (a string) for delimiters, so declare

Code:

char *delim1 = ":";

Thank you. Those fixes got it working. But why do I get this warning: passing arg 1 of `strtok' makes integer from pointer without a cast


this is on the line

Code:

tokenPtr = strtok(line,delim1);

that get rid of that warning, but created a new one.

warning: passing arg 1 of `strtok' makes integer from pointer without a cast