Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

#include <stdio.h>
#include <stddef.h>   /* NULL */

int main(void)
{
    int  value = 42;
    int *ptr   = &value;   /* ptr holds the address of value */

printf("value     = %d
",  value);
    printf("&value    = %p
",  (void *)&value);
    printf("ptr       = %p
",  (void *)ptr);      /* same address */
    printf("*ptr      = %d
",  *ptr);             /* 42           */

/* Modifying through a pointer */
    *ptr = 100;
    printf("value after *ptr=100: %d
", value);   /* 100          */

/* Pointer to pointer */
    int **pptr = &ptr;
    printf("**pptr    = %d
", **pptr);            /* 100          */

/* Null pointer check */
    int *p = NULL;
    if (p == NULL) {
        printf("p is NULL — safe, not dereferencing
");
    }

/* sizeof a pointer (platform-dependent) */
    printf("sizeof(int *) = %zu bytes
", sizeof(int *));

/* Pointer comparison */
    int arr[5] = {1, 2, 3, 4, 5};
    int *start = arr;
    int *end   = arr + 5;
    printf("Elements via comparison: ");
    for (int *q = start; q < end; q++)
        printf("%d ", *q);
    printf("
");

return 0;
}