Thread: Help with a function (ptr_explode)

Im trying to make a function that will split the words (like perl's split and php's explode), but im getting a couple of errors which I don't understand.

Errors:

Code:

$ gcc -W -Wall ptr_explode.c -o ptr_explode
ptr_explode.c: In function `ptr_explode':
ptr_explode.c:25: warning: `return' with a value, in function returning void
ptr_explode.c: In function `main':
ptr_explode.c:33: error: void value not ignored as it ought to be
ptr_explode.c:36: warning: passing arg 1 of `puts' makes pointer from integer without a cast

Code:

Code:

#include <stdio.h>
#include <string.h>

void ptr_explode(char *ptr) 
{
    //char *ptr = "a pointer with a buch of words un fun funf unf ";
    
    /* first 'convert' the pointer into a string so that we can use strtok */ 
    int      ptrlen = strlen(ptr);
    char     string[ptrlen];
    strcpy(string, ptr);

    char     *result = NULL;
    int      ntokens = 0;
    char     words[128][256];
 
    result = strtok(string, " ");
    while (result != NULL) {
        strcpy(words[ntokens++], result);
        result = strtok(NULL, " ");
    }
    
    // puts(words[1]);
    
    return words;
}

int main(void)
{
    char *ptr = "a pointer with a buch of words un fun funf un";
    char *exploded;
 
    exploded = ptr_explode(ptr);
 
    // supposed to print the 2nd word ("pointer")
    puts(exploded[1]);
 
    return 1;
}

And here's the original code that works (and compiles without a single error) which im trying to make into a function:

Code:

#include <stdio.h>
#include <string.h>

int main(void)
{
    char *ptr = "a pointer with a buch of words un fun funf unf ";
    int wtf = strlen(ptr);
    char string[wtf];
    strcpy(string, ptr);
    char *result = NULL;

    int  ntokens = 0;
    char words[256][256];
    result = strtok(string, " ");
    while (result != NULL) {
        strcpy(words[ntokens++], result);
        result = strtok(NULL, " ");
    }
    // prits the second and third word ("pointer", "width")
    puts(words[1]);
    puts(words[2]);
    return 0;
}

If I remember correctly, the reason why void functions can't return values or be used in expressions is because they emulate procedures (ie functions that don't return values) from other programming languages. I say emulate because C only has functions, not procedures.

You need to think about what the function does exactly. It appears to populate a 2D array with words. Thus, you need a way to return this 2D array. Now, any local variable is destroyed when its function ends. That means you can't use a local 2D array like you're doing. You'll need to dynamically allocated space for an array, allocate a line for each word, fill that word, and move to the next. When you're all done, you'll need to return a pointer to that.

Code:

char **splodie( char * );

There's a prototype to work with. Have fun.


Quzah.