Variables

Variables are named containers used to store data in a program. In Go, they are declared using the var and const keywords.

  • var: Used to declare variables that can be reassigned to new values later in the program.

  • const: Used to declare constants whose values cannot be changed once defined.

Variables declared using var can either use the keyword itself or the shorthand := syntax (within functions). Constants, declared with const, must be initialized at declaration and cannot use shorthand syntax.

package main

import "fmt"

// Global scope variables
var a int = 0           // initialized variable
var b int               // uninitialized (defaults to 0)

func main() {
    c := "shorthand syntax" // shorthand only works inside functions
    const pi = 3.14         // constant must be initialized at declaration
    fmt.Println(a, b, c, pi)
}

Uninitialized variables receive their type’s zero value by default (e.g., 0, “”, false)

Data Types

Go provides three primary categories of data types:

Numeric Types

  • Integers:
    Signed: int, int8, int16, int32, int64
    Unsigned: uint, uint8, uint16, uint32, uint64

  • Floating-point: float32, float64

  • Complex numbers: complex64, complex128

String Type

  • A string is an immutable sequence of bytes, typically UTF-8 encoded.

Boolean Type

  • Represents truth values: true or false

Quick Notes