Trusted answers to developer questions
Trusted Answers to Developer Questions

Related Tags

go
communitycreator

What are functions in Go language?

Shubham Singh Kshatriya

What is a function?

A function is a block of code or a collection of statements compartmentalized together to perform a specific task. It takes an input, does some processing, and produces an output.

Every Go program has at least one function, i.e., main().

Function declaration

We can declare a function using the func keyword.

Syntax

func functionName (parameters) returnType {
    // body
}

Besides the func keyword, a function declaration contains:

  • functionName: Specifies the name of the function.
  • parameters: Specifies the list of parameters that the function accepts. It contains the name and the type of each parameter separated by a comma. It is optional.
  • returnType: Specifies the type of value that function returns. It is optional.
  • body: Specifies what the function does.

Function invocation/calling

To execute a function, we need to call or invoke it.

We need to pass the required parameters along with the function name inside the main() function. If the function returns a value, we can also store it in a variable.

Example 1

The below example shows how to declare and invoke a function in Golang.

package main

import "fmt"

// declaring function "perimeter"
func perimeter(num1, num2 int) int {
   return num1 + num2 
}

func main() {
   // invoking function "perimeter"
   res := perimeter(20, 10)

   // print the res on console
   fmt.Printf( "Perimeter of rectangle is : %d\n", res)
}

Explanation

In the above example, from line 6 to line 8, we have declared a function perimeter() that takes two parameters, num1 and num2, and returns their sum.

Inside the main(), at line 12, we have invoked the perimeter function and assigned the value returned by it to res variable.

At line 15, we have output the res on the console.

Function returning multiple values

A Go function can return multiple values as well. All the values that needs to be returned should be separated by a comma.

Example 2

The below example shows how to return multiple values from a function in Golang.

package main

import "fmt"

// declare function "getPerimeterAndArea"
func getPerimeterAndArea(num1, num2 int) (int, int) {
   perimeter := num1 + num2
   area := num1 * num2
   
   // returning multiple values
   return perimeter, area 
}

func main() {
   // invoke function "getPerimeterAndArea"
   perimeter, area := getPerimeterAndArea(20, 10)
   
   // print perimeter and area on console
   fmt.Printf( "Perimeter of rectangle is : %d\n", perimeter)
   fmt.Printf( "Area of rectangle is : %d\n", area)
}

In the above example, from line 6 to line 12, we have declared a function getPerimeterAndArea() that takes two parameters num1 and num2, calculates the perimeter and area, and then returns both of them.

Inside the main(), at line 16, we have invoked the getPerimeterAndArea() function and assigned the value returned by it to perimeter and area variable respectively.

At line 19 and line 20, we have output the perimeter and area on the console.

RELATED TAGS

go
communitycreator

CONTRIBUTOR

Shubham Singh Kshatriya
RELATED COURSES

View all Courses

Keep Exploring