Control Flow

if and else in Go work as you'd expect, with one small difference from many other languages: the condition never needs parentheses, though the braces are always required, even for a single statement.

package main

import "fmt"

func main() {
	age := 20
	if age >= 18 {
		fmt.Println("You are an adult")
	} else {
		fmt.Println("You are a minor")
	}
}

You are an adult

for is Go's only loop keyword

Go has no while or do-while — for covers every loop shape. With all three clauses, it's a classic counting loop; drop the init and post clauses and keep just a condition, and it behaves exactly like a while loop in any other language.

package main

import "fmt"

func main() {
	for i := 0; i < 3; i++ {
		fmt.Println("counting up:", i)
	}

	n := 3
	for n > 0 {
		fmt.Println("counting down:", n)
		n--
	}
}

counting up: 0
counting up: 1
counting up: 2
counting down: 3
counting down: 2
counting down: 1

Next: arrays and slices — Go's fixed-size and growable collection types.