Ok, C Board, what am I doing wrong? (Linked lists)

[Babkockdood]

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

typedef struct node {
	int value;
	struct node *next;
} block;

int main(void) {
	block *root = NULL;
	block *c;
	int x;
	c = root;
	for (x = 0; x < 10; x++) {
		c = (block *)malloc(sizeof(block));
		c->value = (x*4);
		// 0, 4, 8, 12, 16, 20, etc
		c = c->next;
	}
	for (c = root; c; c = c->next)
		printf("%d\n", c->value);
	return 0;
}

The first for loop is supposed to allocate memory for 10 list items, and assign the value inside the list item to a multiple of four.

The second for loop is supposed to go to the beginning of the list and print each list item.

This program compiles fine, but it doesn't output anything.

[anduril462]

c = c->next

You just allocated memory for c, but it's uninitialized. That means c->next contains garbage. You then assign that garbage to c and lose your handle to the memory you just malloc'ed (memory leak). You can't add to the end of the list without either a temp pointer that you use to iterate to the last node, or a tail pointer that you always maintain as pointing to the last node in the list.

for x from 0 to 9
    c = malloc
    c->value = x*4
    c->next = NULL
    if (root == NULL) // empty list
        root = c
    else
        temp = last node in list
        temp->next = c
        update tail pointer if you have one