/*
    MALLOC DEMO #2 Illustrates:
	use of malloc
	use of free
	passing pointers into functions
	the ** prototype (pointer to a pointer)
	scanf("%s", ... ) which is vulnerable to overflow
*/

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

#define MAX_WORD_LENGTH 30

void getWord(char *word);  /* word is address of pointer (ptr to a ptr) */


int main(int argc, char *argv[])
{
    char *word;  /*  a.k.a pointer to String */

    getWord(word);  /* must pass word's address (why?) */
    printf("Back from getWord. String is %s\n", word);
    free(word);
    word = NULL;  /* NULL'ing after free'ing is a not a bad practice */

    return 0;
}

/* Takes 1 arg: pointer to pointer to char (address of a char pointer)
   modifies the pointer whose address is in passed by dereferencing the pointer
*/
void getWord(char *word)
{

    word = malloc(MAX_WORD_LENGTH * sizeof(char));
    if (word==NULL)  /* ALWAYS CHECK FOR NULL AFTER malloc */
    {
	printf("malloc failed: Exiting Program!\n\n");
	exit(EXIT_FAILURE);
    }

    printf("Enter a word (<%d chars): ", MAX_WORD_LENGTH);
    fflush(stdout);
    scanf("%s", word);  /* DANGER: vulnerable to buffer overflow */
}