Why in this code there is no output? I think it does not mean, it outputs error.

Question

#include <stdio.h>

int main() {
int arr[50]={0,1,2, [47]=47,48,49};
}

Answer 1

because this code declares an array, but does not output it)

Answer 2

Pls assist me sir
Write a program to determined if a number enter in a keyboard is a prime number or not using c++ language