cant fix a logical error in a recursion function

If post fix decrement(--x) is equal to (x-1) so why when I change factorial(n-1) to factorial(--n)it gives me a logical error of output = 0

#include<stdio.h>

int factorial (int n) {
    int fact=1;
    if (n>=1) {
        fact=n*factorial(n-1);
    }
    return fact;
}

void main (void) {
    int x , y ;
    printf("Please Enter a Number : ");
    scanf("%d",&x);
    y=factorial(x);
    printf("Factorial = %d ",y);
}

>Solution :

factorial(n-1) to factorial(–n)it gives me a logical error of output
= 0

It is undefined by C language standard.

But probable explanation of the observable behaviour is: if n == 1 then

fact=n*factorial(--n);

n will become zero before calling factorial. So if n == 1 then it will become

fact=0*factorial(0);

Which is always 0.