freeCodeCamp/guide/english/go/if/index.md

title
If in Go

If in Go

Go's if statements are like its for loops; the expression need not be surrounded by parentheses ( ) but the braces { } are required.

func sqrt(x float64) string {
	if x < 0 {
		return sqrt(-x) + "i"
	}
	return fmt.Sprint(math.Sqrt(x))
}

Like for, the if statement can start with a short statement to execute before the condition.

Variables declared by the statement are only in scope until the end of the if.

func pow(x, n, lim float64) float64 {
	if v := math.Pow(x, n); v < lim {
		return v
	}
	return lim
}

If and else

Variables declared inside an if short statement are also available inside any of the else blocks.

package main

import (
	"fmt"
	"math"
)

func pow(x, n, lim float64) float64 {
	if v := math.Pow(x, n); v < lim {
		return v
	} else {
		fmt.Printf("%g >= %g\n", v, lim)
	}
	// can't use v here, though
	return lim
}

func main() {
	fmt.Println(
		pow(3, 2, 10),
		pow(3, 3, 20),
	)
}

Running the above program produces an output similar to the following output -

$ go run if.go
27 >= 20
9 20