# Variables — C Programming

Source: https://www.geekswithgeeks.com/en/c/c-variables

> Named, typed pieces of memory.

## Declare with a type

You must state the type. Uninitialised variables hold garbage.

```c
int   age   = 25;
float price = 9.99f;
char  grade = 'A';
int   score;        // unknown until assigned
score = 100;
```

## Constants

`const double PI = 3.14159;` cannot be reassigned. `#define MAX 50` is a compile-time text swap.

## Printing them

`printf` uses format specifiers: `%d` int, `%f` float, `%c` char, `%s` string. `printf("n = %d\n", n);`