# Pointer Basics — C Programming

Source: https://www.geekswithgeeks.com/en/c/c-pointers-basics

> A variable that stores a memory address.

## A pointer is a house address

A normal variable is like a house holding a value. A **pointer** is a piece of paper with that house's **address** written on it — not the house itself.

## & and * — address-of and dereference

`&x` gives the address of `x`. `*p` reads (or writes) the value at the address `p` holds.

```c
int x = 10;
int *p = &x;      // p holds x's address

printf("%d\n", x);   // 10
printf("%d\n", *p);  // 10 -- value at that address

*p = 20;              // change x through p
printf("%d\n", x);   // 20
```

Output:

```
10
10
20
```

## Declared type matters

`int *p` means "p points to an int", not "*p is int". The `*` in a declaration is part of the pointer's type, telling C how many bytes to read/write through it.