date: 22-May-2024
updated: 22-May-2024
status: #status/unprocessed
type: #type/doc
area: #area/cultivation#area/tech
keyword: #keyword/zig

How do you declare variable in zig?

Well, that’s pretty simple. Here’s an example:

const foo: u8 = 1;
var bar: u8 = 2;

There are two ways of delaring a variable as you can see

• const - for immutable variable or in simple term a variable that cannot be changed
• var - for mutable variable or variable that can be changed later on in the program

Data Type

In this chapter, we’ll only talk about simple primitive type. Integer, Boolean, String (maybe)…

Integer

The integer type comes in two form u(n) and i(n), see the example below:

// Here we are declaring that foo is an unsigned 8bits integer.
// Unsigned integer can only contains positive number.
// 8 bits is the amount of memory allocated to foo.
const foo: u8 = 3;
const noNegative: u8 = -2; // Error: cannot be negative
const too_big: u8 = 10000; // Error: number too big
 
// We'll talk more about the bit thingy later.
// Let's see how we can have negative number first.
const negative_foo: i8 = -2; // OK

As you can tell, u(n) and i(n) behave identically, the big difference is that u(n) cannot have negative number, while i(n) can!!

What about the bit thingy? Well that’s the amount of memory allocated for the number. For example 4 bits meaning 4 spots for the binary number 0000.

• 1 → 0001
• 2 → 0010
• 3 → 0011
• 4 → 0100
• 5 → 0101
• 6 → 0110
• 7 → 0111
• 8 → 1000
• 9 → 1001
• 10 → 1010
• 11 → 1011
• 12 → 1100
• 13 → 1101
• 14 → 1110
• 15 → 1111

In this case, a u4 can only hold number from 0 - 15.