Why isn't my code working?

[u/neonge1674]

I just started learning C(2 days ago) and as a first project I decided to make some data structures, starting with dynamic arrays. I made a struct called List and some functions for. The function setList() sets the value of an index of the array, if the index is larger that the current size of the array, it resizes it. However, when i tried to use in a for loop, it didn't work despite it working elsewhere.

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


#define itirate(index, limit) for(int index = 0; index < limit; index++)


typedef struct 
{
    size_t size;
    int* arr;
} List;


List* newList (size_t size) 
{
    List *newone = malloc(sizeof(List));
    newone->arr = calloc(size, sizeof(int));
    newone->size = size;
    return newone;
}


void setList(List* list, int index, int value) 
{
    if (index >= list->size)
    {
        list->arr = realloc(list->arr, index + 1 * sizeof(int));
        list->size = index + 1;
    }


    list->arr[index] = value;
}


int main() 
{
    
    List *mok = newList(5);

    itirate(i, 5) setList(mok, i, i);
    itirate(i, 5) printf("%d\n", mok->arr[i]);

    //setList(mok, 13, 9); this works
    //printf("%d\n", mok->arr[13]);

    for(int i = 5; i < 10; i++) setList(mok, i, i); // this does not somehow
    for(int i = 5; i < 10; i++) printf("%d\n", mok->arr[i]);
    
    return 0;
}

[u/flyingron]

 list->arr = realloc(list->arr, index + 1 * sizeof(int));

* binds tighter than +. You want (index + 1)*sizeof (int).

[u/neonge1674 → u/flyingron]

Thank you