If/Else语句(If/Else)

在Go中，使用if和else进行分支判断非常直观。

Branching with if and else in Go is straight-forward.

下面是一个基本的例子。

Here’s a basic example.

package main

import "fmt"

func main() {
	if 7%2 == 0 {
		fmt.Println("7 is even")
	} else {
		fmt.Println("7 is not even")
	}
}

package main

import "fmt"

func main() {
	if 7%2 == 0 {
		fmt.Println("7 is even")
	} else {
		fmt.Println("7 is not even")
	}
}

你可以使用没有else的if语句。

You can have an if statement without an else.

package main

import "fmt"

func main() {
	if 8%4 == 0 {
		fmt.Println("8 is divisible by 4")
	}
}

package main

import "fmt"

func main() {
	if 8%4 == 0 {
		fmt.Println("8 is divisible by 4")
	}
}

一个语句可以位于条件语句之前；在该语句中声明的任何变量都可以在当前分支和所有后续分支中使用。

A statement can precede conditionals; any variables declared in this statement are available in the current and all subsequent branches.

package main

import "fmt"

func main() {
	if num := 9; num < 0 {
		fmt.Println(num, "is negative")
	} else if num < 10 {
		fmt.Println(num, "has 1 digit")
	} else {
		fmt.Println(num, "has multiple digits")
	}
}

package main

import "fmt"

func main() {
	if num := 9; num < 0 {
		fmt.Println(num, "is negative")
	} else if num < 10 {
		fmt.Println(num, "has 1 digit")
	} else {
		fmt.Println(num, "has multiple digits")
	}
}

请注意，在Go中，条件语句不需要括号，但是必须有大括号。

Note that you don’t need parentheses around conditions in Go, but that the braces are required.

Go中没有三元if语句，所以即使是基本条件，你也需要使用完整的if语句。

There is no ternary if in Go, so you’ll need to use a full if statement even for basic conditions.

运行

package main

import "fmt"

func main() {

	if 7%2 == 0 {
		fmt.Println("7 is even")
	} else {
		fmt.Println("7 is odd")
	}

	if 8%4 == 0 {
		fmt.Println("8 is divisible by 4")
	}

	if num := 9; num < 0 {
		fmt.Println(num, "is negative")
	} else if num < 10 {
		fmt.Println(num, "has 1 digit")
	} else {
		fmt.Println(num, "has multiple digits")
	}
}

package main

import "fmt"

func main() {

	if 7%2 == 0 {
		fmt.Println("7 is even")
	} else {
		fmt.Println("7 is odd")
	}

	if 8%4 == 0 {
		fmt.Println("8 is divisible by 4")
	}

	if num := 9; num < 0 {
		fmt.Println(num, "is negative")
	} else if num < 10 {
		fmt.Println(num, "has 1 digit")
	} else {
		fmt.Println(num, "has multiple digits")
	}
}

bash

go run 06-if-else.go 
# 7 is odd
# 8 is divisible by 4
# 9 has 1 digit

go run 06-if-else.go 
# 7 is odd
# 8 is divisible by 4
# 9 has 1 digit

运行 ​

运行