Pointers

Pointers

A pointer is a variable that stores the address of another variable. Pointers point to data.

Declaring a pointer

Use * in the declaration:

int x = 25;        // a normal int
int *p = &x;       // pointer that holds x's address

p doesn't hold the value 25; it holds where 25 lives.

Reading the address

printf("%p", p);          // the address of x
printf("%d", x);          // 25

Dereferencing with *

The * operator (dereference) goes to the address and reads the value:

printf("%d", *p);         // 25, the value at p's address

Summary

• * in a declaration: "pointer to".
• & gets an address.
• * on a pointer: dereference, get the value.

TL;DR

• A pointer stores an address, not a normal value.
• Declare with int *p;.
• p = address; *p = value at that address.
• & takes an address; * reads through one.