Go语言的控制流程

使用if语言的程序清单如下：

package main

import(
  "fmt"
)
func main(){
  b:=true
  if b{
    fmt.Println("b is true!")
  }
}

运行结果如下：

b is true!

使用else语句的代码清单如下：

package main

import(
  "fmt"
)
func main(){
  b:=false
  if b{
    fmt.Println("b is true!")
  } else{
    fmt.Println("b is false!")
  }
}

运行结果如下：

b is false!

使用else if语句的程序清单如下：

package main

import(
  "fmt"
)
func main(){
  i:=2
  if i==3{
    fmt.Println("i is 3")
  } else if i==2{
    fmt.Println("i is 2")
  }
}

运行结果如下：

i is 2

使用switch语句的程序清单：

package main

import(
  "fmt"
)
func main(){
  i:=2
  switch i{
  case 2:
    fmt.Println("Two")
  case 3:
    fmt.Println("Three")
  case 4:
    fmt.Println("Four")
  }
}

运行结果如下：

Two

在switch语句中添加default case的程序清单：

package main

import(
  "fmt"
)
func main(){
  s:="c"
  switch s{
  case "a":
    fmt.Println("The letter a!")
  case "b":
    fmt.Println("The letter b!")
  default:
    fmt.Println("I don't recognize that letter!")
  }
}

运行结果如下：

I don't recognize that letter!

使用for语句进行循环的程序清单如下：

package main

import(
  "fmt"
)
func main(){
  i:=0
  for i<10{
    i++
    fmt.Println("i is",i)
  }
}

运行结果如下：

i is 1
i is 2
i is 3
i is 4
i is 5
i is 6
i is 7
i is 8
i is 9
i is 10

一个包含初始化语句和后续语句的for语句的程序清单如下：

package main

import(
  "fmt"
)
func main(){
  for i:=0;i<10;i++{
    fmt.Println("i is",i)
  }
}

运行结果如下：

i is 0
i is 1
i is 2
i is 3
i is 4
i is 5
i is 6
i is 7
i is 8
i is 9

包含range子句的for语句的程序清单如下：

package main

import(
  "fmt"
)
func main(){
  numbers:=[]int{1,2,3,4}
  for i,n:= range numbers {
    fmt.Println("The index of the loop is",i)
    fmt.Println("The value from the array is",n)
  }
}

//i和n是迭代变量。i用于存储索引值，n用于存储来自数组中的值。
//迭代变量从0开始。

运行结果如下：

The index of the loop is 0
The value from the array is 1
The index of the loop is 1
The value from the array is 2
The index of the loop is 2
The value from the array is 3
The index of the loop is 3
The value from the array is 4

使用defer语句的程序清单如下：

package main

import(
  "fmt"
)
func main(){
  defer fmt.Println("I am run after the function completes")
  fmt.Println("Hello World!")
}

运行结果如下：

Hello World!
I am run after the function completes

使用多条defer语句的程序清单：

package main

import(
  "fmt"
)
func main(){
  defer fmt.Println("I am the first defer statement")
  defer fmt.Println("I am the second defer statement")
  defer fmt.Println("I am the third defer statement")
  fmt.Println("Hello World!")
}

运行结果如下：

Hello World!
I am the third defer statement
I am the second defer statement
I am the first defer statement