Making my own slice function for c but getting absurd value for some slices

I am trying to make my own slice function, but for some value like (0,15) it is printing absurd value at the end. It is working fine for other inputs. Here is my code:

#include<stdio.h>

void slice(int a, int b, char *str) {
    char new[b - a];

    for (int i = 0; i < b - a; i++) {
        new[i] = str[a + i];
    }

    puts(new);
}

int main() {
    char str[] = { "My name is Ayush Anand" };
    slice(0, 15, str);
    
    return 0;
}

What’s wrong?

>Solution :

There should be extra room for a null-terminator. So, at the (b – a)th index, add one.

for (int i = 0; i < b - a; i++)
    new[i] = str[a + i];

new[b - a] = 0; // Null-terminator

As mentioned in one of the comments, a > b is invalid. So, add a condition before the declaration of the new string.

if (a > b) {
    fprintf(stderr, "a > b error");
    return;
}
char new[b - a];
...