Using strtok on separate functions

This is a discussion on Using strtok on separate functions within the C Programming forums, part of the General Programming Boards category; I've used strtok() before to parse a string, but for some reason I cannot seem to use it in separate ...

  1. #1
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    Sep 2004
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    Using strtok on separate functions

    I've used strtok() before to parse a string, but for some reason I cannot seem to use it in separate functions correctly. I'm trying to separate strings in one function and initialize them in the calling function. Can someone tell me where I'm going wrong?

    Code:
    void get_tokens(char *line, char *lbl, char *opertr, char *opernd){    
        lbl=strtok(line, " ");
        opertr = strtok(NULL, " ");    
        opernd = strtok(NULL, " ");
    }  
    
    void pass1(){
       char  inp_line[INP_LENGTH + 1],
             label[NAME_LENGTH + 1],    
             oper[OP_LENGTH + 1],  
             opnd[OPND_LENGTH + 1]; 
       
       get_tokens(inp_line, label, oper, opnd);
    }

  2. #2
    & the hat of GPL slaying Thantos's Avatar
    Join Date
    Sep 2001
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    5,681
    Simply put: strtok() returns a pointer but it won't actually copy over the data. Try capturing the return value in a different point and then use strcpy() afterwards to copy the data over.

    Example:
    Code:
    void get_tokens(char *const line, char *const lbl, char *const opertr, char *const opernd) {
      char *temp = strtok(line, " ");
      strcpy(lbl, temp);
      temp = strtok(NULL, " ");
      strcpy(opertr, temp);
      /* ... */
    }
    Now I should mention that you really should check the return value of strtok() for NULL before calling strcpy().

  3. #3
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    Sep 2004
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    Thanks a lot Thantos. For some reason I didn't even think of using strcpy( ). That did the trick.

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