Variables and Data Types

By: Mustafif Khan

Language: Zig

Variables and Data Types

Var vs Const

In Zig we have two ways to create variables which differ from mutability, where var declares a mutable variable and const is immutable. Most cases will only require an immutable variable and its recommended to use const in most cases unless mutability is required, this improves security in your program and thus a key reason languages like Swift and Rust also provide abstractions like this.

Declaring a Variable

Now that we understand the difference between var and const, to declare a variable we can either declare its datatype explicitly (using the : operator) or implicitly. To look at the difference consider the following:

// syntax: <var/const> <ident>: <type> = <value>;

// Explicitly declared a floating point variable 
const float_num: f64 = 20.4; // data type f64

// Implicitly declared a floating point variable 
const float2 = 50.4; // data type comptime_float

Variables cannot be left undeclared, if you do not have a known value when needing to declare the value you may use the undefined keyword.

Primitive Data Types

Type	C Equivalent	Description
`i8`	`int8_t`	Signed 8-bit integer
`u8`	`uint8_t`	Unsigned 8-bit integer
`i16`	`int16_t`	Signed 16-bit integer
`u16`	`uint16_t`	Unsigned 16-bit integer
`i32`	`int32_t`	Signed 32-bit integer
`u32`	`uint32_t`	Unsigned 32-bit integer
`i64`	`int64_t`	Signed 64-bit integer
`u64`	`uint64_t`	Unsigned 64-bit integer
`i128`	`__int128`	Signed 128-bit integer
`u128`	`unsigned __int128`	Unsigned 128-bit integer
`isize`	`intptr_t`	Signed pointer-sized integer
`usize`	`uintptr_t`, `size_t`	Unsigned pointer-sized integer
`16`	`_Float16`	16-bit floating point (10-bit mantissa) IEEE-754-2008 binary16
`f32`	`float`	32-bit floating point (23-bit mantissa) IEEE-754-2008 binary32
`f64`	`double`	64-bit floating point (52-bit mantissa) IEEE-754-2008 binary64
`f80`	`double`	80-bit floating point (64-bit mantissa) IEEE-754-2008 80-bit extended precision
`f128`	`_Float128`	128-bit floating point (112-bit mantissa) IEEE-754-2008 binary128
`bool`	`bool`	True or false
`comptime_int`	(none)	Only allowed for comptime-known values. The type of integer literals.
`comptime_float`	(none)	Only allowed for comptime-known values. The type of float literals.

These are provided by the official Zig Documentation, for more information check it out here.