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go语言中没有do-while，switch更加灵活，支持初始化子语句，这篇文章中将会就go的循环/分支等流程控制语句进行简单介绍。

if语句

写法和其他语言基本一致，不过多层else if的时候需要注意{要写在一行，否则通不过编译也无法进行go fmt

例子代码

[root@liumiaocn goprj]# cat basic-if.gopackage mainfunc main() {        //pattarn 1        score := 75        if score < 60 {                println("Grade: D")        } else if score < 70 {                println("Grade: C")        } else if score < 80 {                println("Grade: B")        } else if score <= 100 {                println("Grade: B")        } else {                println("Grade: undefined")        }        //pattarn 2        if score := 45; score < 60 {                println("Grade: D")        } else if score < 70 {                println("Grade: C")        } else if score < 80 {                println("Grade: B")        } else if score <= 100 {                println("Grade: B")        } else {                println("Grade: undefined")        }}[root@liumiaocn goprj]#

执行结果

[root@liumiaocn goprj]# go run basic-if.goGrade: BGrade: D[root@liumiaocn goprj]#

switch-case语句

例子代码

[root@liumiaocn goprj]# cat basic-switch.gopackage mainimport "fmt"func main() {        //pattarn 1        weekday := "FRI"        switch weekday {        case "MON":                fmt.Println("Monday...")        case "TUE":                fmt.Println("Tuesday...")        case "WED":                fmt.Println("Wednesday...")        case "THU":                fmt.Println("Thursday...")        case "FRI":                fmt.Println("Friday...")        case "SAT":                fmt.Println("Saterday...")        case "SUN":                fmt.Println("Sunday...")        default:                fmt.Println("Default branche...")        }        //pattarn 2        switch weekday := "SUN"; weekday {        case "MON":                fmt.Println("Monday...")        case "TUE":                fmt.Println("Tuesday...")        case "WED":                fmt.Println("Wednesday...")        case "THU":                fmt.Println("Thursday...")        case "FRI":                fmt.Println("Friday...")        case "SAT":                fmt.Println("Saterday...")        case "SUN":                fmt.Println("Sunday...")        default:                fmt.Println("Default branche...")        }        //pattarn 3        score := 75        switch {        case score < 60:                fmt.Println("Grade D...")        case score <= 70:                fmt.Println("Grade C...")        case score <= 80:                fmt.Println("Grade B...")        case score <= 90:                fmt.Println("Grade B...")        default:                fmt.Println("Default branche...")        }        //pattarn 4        var obj interface{}        obj = "Hello World"        switch obj.(type) {        case int:                fmt.Println("This is a int type ...")        case string:                fmt.Println("This is a string type...")        default:                fmt.Println("Default branch...")        }}[root@liumiaocn goprj]#

执行结果

[root@liumiaocn goprj]# go run basic-switch.goFriday...Sunday...Grade B...This is a string type...[root@liumiaocn goprj]#

for语句

例子代码

[root@liumiaocn goprj]# cat basic-for.gopackage mainfunc main() {        //pattarn 1        for level := 0; level < 10; level++ {                for cnt := 0; cnt < 10-level; cnt++ {                        print(" ")                }                for ascnt := 0; ascnt < level; ascnt++ {                        print("*")                }                println("")        }        //pattarn 2        level := 0        for level < 10 {                for cnt := 0; cnt < 10-level; cnt++ {                        print(" ")                }                for ascnt := 0; ascnt < 2*level-1; ascnt++ {                        print("*")                }                println("")                level++        }        //pattarn 3        /*                for {                        println("please don try this one unless you want to test your cpu usage")                }        */}[root@liumiaocn goprj]#

执行结果

[root@liumiaocn goprj]# go run basic-for.go         *        **       ***      ****     *****    ******   *******  ******** *********         *        ***       *****      *******     *********    ***********   *************  *************** *****************[root@liumiaocn goprj]#

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