Thread: c recursion in structures

hello guys, i read someone else's code which works. then i wrote this one myself to see if i can incorporate recursion in adding nodes to a linked list structure. in the debugger after the loop ought to end, it revives itself, assigns value 1 to num_m and starts all over again so irrespective of num_m, length() always return 2. this is beyond my comprehension. I've been on this for 3hrs and no luck

Code:

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



struct node{
    int a;
    struct node *next;
};

int add_node(struct node **head, int val, int num_m);
int length(struct node *);

int main(){

struct node *head = NULL;
struct node first;
first.a = 5;
first.next = NULL;
head = &first;
printf("%p", &first);
add_node(&head, 5, 2);
int count = length(head);

printf("lenght is %d", count);

}

int add_node(struct node **head, int val, int num_m){
    int i;
    int x = 0;
    x = num_m;
    struct node *new_node;
    struct node *temp;
    while(x > 0){
        new_node = (struct node *)malloc(sizeof(struct node));
        new_node->a = val;
        new_node->next = NULL;
        (*head)->next = new_node;
        x--;

        if (x > 0){
            i = val+2;
            add_node(&new_node, i, x);
        }

    }
}

int length(struct node *head){
    if(head->next == NULL)
        return 1;
    else{
        return (1 + length(head->next));
    }
}

If add_node is supposed to add num_m nodes to the list then you've made the mistake of using a loop and recursion at the same time. You want to just use the recursion. Your base case would be num_m <= 0 in which case you just return. The recursive call would pass in num_m - 1.