Constant In Golang 2019

In the below program we create the variable x and assign value 10 after this we again assign value 12 to the same variable x and we print this on the console which is working fine. By using this you will know we can change the value of variable anytime in our program.

Code:

package main

import (
    "fmt"

    "./utilitypackage"
)

func main() {

    //fmt.Println(utilitypackage.Reverse("sagar"))
    //utilitypackage.CreateDataTypes()

    var x = 10
    fmt.Println("val is x", x)

    x = 12
    fmt.Println("changed val is x", x)

    fmt.Println("\n called in main ", utilitypackage.Name)

}

Geral Variable In Golang.png


Now we will create constant and check what will happen to see below image :


Constant In Golang.png


Below is the program for that

Code:

package main

import (
   "fmt"

   "./utilitypackage"
)

func main() {

   //fmt.Println(utilitypackage.Reverse("sagar"))
   //utilitypackage.CreateDataTypes()

   const x = 10
   fmt.Println("val is x", x)

   x = 12
   fmt.Println("changed val is x", x)

   fmt.Println("\n called in main ", utilitypackage.Name)

}

When you declared a constant in your program you can’t change the value of this variable again in your program. If you try to change the value of this it will throw an error.

Point to remember when you declared a constant you need to assign value to that variable at the time of declaration else it will throw an error.

See below image

Constant In Golang.png



Different way’s to declare constant variables in golang

Code:

package main

import "fmt"

const b string = "sagar jaybhay"
const a = 42

const (
   v = iota
   j = iota * 10
   k = iota * 10
)

func main() {

   const aa = "sagar"
   fmt.Println("hello brother")
   println(v)
   println(j)
   println(k)
}
[/SIZE]

Different Ways to declare Constant with iota.png