Variables & Types¶

A variable is a named storage location. You give it a name, store a value in it, and use the name to get the value back later.

Declaring a variable¶

In C, you must declare a variable before you use it. A declaration tells the compiler the variable's name and type:

int score;

This reserves space for one integer called score. It does not have a value yet.

Declaring and assigning in one step¶

int score = 0;

Now score starts with the value 0.

Common types in these labs¶

`int` — integer¶

A whole number, positive or negative:

int temperature = -5;
int level = 42;

`unsigned` — non-negative integer¶

An integer that can only be zero or positive. Useful when you know a value (like a sensor reading) will never be negative:

unsigned reading = 512;

Updating a variable¶

You can assign a new value to a variable any time after it is declared:

int score = 0;
score = 10;       // score is now 10
score = score + 5; // score is now 15

The right-hand side is evaluated first, then the result is stored in the variable on the left.

Example: a simple counter¶

int count = 0;

// ... later, inside loop() ...
count = count + 1;
printf("Count so far: %d\n", count);

This keeps a running count of how many times loop() has run. It has nothing to do with joysticks or motors — it's just a counter — but the same pattern applies anywhere you need to remember a value between iterations.