Summary - Pointer basics

Combine &, * and NULL to write a swap function.

Summary: Pointer basics

In this group you saw the basics of pointers. A pointer holds a memory address; & takes the address, * accesses the value.

Now let's combine these in one task.

Define int x = 15;. Bind with int *ptr = &x;. Print the value ptr points to with printf("%d\n", *ptr);. Output should be 15.

Show example solution

#include <stdio.h>

int main(void) {
    int x = 15;
    int *ptr = &x;
    printf("%d\n", *ptr);
    return 0;
}

NULL check

int *p = NULL;
if (p ____) { /* not safe */ }

Show answer

int *p = NULL;
if (p == NULL) { /* not safe */ }