Const - General Questions

What does const int *p; declare?

Which is the main difference between const and #define constants?

What will be the output of the program?

#include <stdio.h>

int main(void) {
    const int n = 5;
    int arr[n];
    printf("%zu\n", sizeof(arr) / sizeof(arr[0]));
    return 0;
}

Must a const variable be initialised when declared?

What will be the output of the program?

#include <stdio.h>

int main(void) {
    const char *s = "const";
    s++;
    printf("%s\n", s);
    return 0;
}