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Controlling Program Flow of golang

 


Overview

In this blog I am going to talk about the topic below.

Loop

You can use loop as below. here i variable is declared inside the loop so the value will be valid in side the loop.

 Example 

      
    package main

    import (
        "fmt"
    )

    func main() {
        for i:=0;i<5;i++{
            fmt.Println(i)
        }

    }

output :

    0
    1
    2
    3
    4
    5

Break in Loop

what Break statement dose is it will break out from the loop. 
      package main

      import (
          "fmt"
      )

      func main() {
          for i:=0;i<5;i++{
              fmt.Println(i)
              if i==2 {
                  break
              }
          }

      }

output :

    0
    1
    2
in the example you can see when loop comes to the point when i == 2 then it break out from the loop and end the program. this why it out put the value of i until it is 2.

Continue in Loop

what Continue statement dose is it will break out from the loop but will continue with the next iteration that loop. but it will ignore every code after that statement. 
  package main
  import ("fmt")

  func main() {
      for i:=0;i<5;i++{
          fmt.Println(i)
          if i==2 {
              continue	
          }
          fmt.Println("hello")
      }
  }

output :

  0
  hello
  1
  hello
  2
  3
  hello
  4
  hello
if you can see, in the example program is not printing the hello string when i == 2. but continues with the loops next iteration. 

Infinity Loop

you can initiate infinite loop as below.
    package main

    import (
        "fmt"
    )

    func main() {
    	i := 1
        for {
            fmt.Println(i)
        }

    }

Collection Loop

you can iterate any collection using normal loop. but go has a very minimalistic way of looping a collection where you can iterate collection in a simple way which is range.
  package main
  import ("fmt")

  func main() {
      array := []string{"hello","world","!!!"}
      marks := map[string]int{"Bangla":80,"English":90,"Science":95}

      for i,v := range array {
          fmt.Println(i,v)
      }

      for i,v := range marks {
          fmt.Println(i,v)
      }
  }

output :

  0 hello
  1 world
  2 !!!
  Bangla 80
  English 90
  Science 95
if you can see in the example. range loop is assigning index and value in variable i and v and printing it.

Switch

Switch on golang is parity much self explanatory. you can understand switch by the example below.
  package main
  package main

  import (
      "fmt"
  )

  func main() {
      nameAgeList := map[string]int{"Alax":18,"Jack":10,"Dani":21}

      for name,age := range nameAgeList {
          switch name {
          case "Alax" :
              fmt.Println("go to collage your age is",age)

          case "Jack" :
              fmt.Println("go to school your age is",age)

          case "Dani" :
              fmt.Println("go to University your age is",age)	
          }

      } 

  }

output :

  go to collage your age is 18
  go to school your age is 10
  go to University your age is 21

Panic

Panic is used in golang where program hits a position that it doesn't knows what to do. i know you can use error and exceptions in go for that but in panic it will terminate the program and report where it hits the problem.
  package main

  import (
      "fmt"
  )

  func main() {
      nameAgeList := map[string]int{"Alax":18,"Jack":19,"Dani":21}

      for name,age := range nameAgeList {
          switch name {
          case "Alax" :
              fmt.Println("go to collage your age is",age)

          case "Jack" :
              if age > 18 {
                  panic("somthing is worng")
              }
              fmt.Println("go to school your age is",age)

          case "Dani" :
              fmt.Println("go to University your age is",age)	
          }

      } 

  }

output :

    go to collage your age is 18
    panic: somthing is worng

    goroutine 1 [running]:
    main.main()
        /tmp/sandbox467193843/prog.go:17 +0x3d1












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