Function in Golang

Function in Golang is an isolated piece of statements that are assigned a unique name and can be used multiple times in your project.

• Advantages of using function
• Signature of a function in Golang
• Write a function that accepts two integer numbers and returns their sum
• Write to function to check if the given number is an even number or not
• Write a function that returns two values
• References

Advantages of using function

• It makes your code more readable.
  • A long piece of code can be broken down into independent small functions and it increases code readability
• It makes your code more organized.
• It removes repetitive code from your application
  • You define a functionality and give it a name of function. The same function can be used in multiple places and it removes repetitive code.

Signature of a function in Golang

A function has five parts

• func keyword of Golang which tells the compiler, we are going to define a function
• Name of the function: Here process is the name of the function
  • You can give any name to your function.
  • Providing meaningful names to the function increases the code readability
• Input Parameters
  • These are the inputs given to a function
  • There is no restriction on the number of input parameter
    • It can be zero
    • It can be one or more than one
  • When you define the input parameter then you need to give two things
    • Name of the input parameter as it will be used with this name inside the function body
    • The data type of the input parameter
• Return Values
  • This defines what things can be returned from the function
  • There is no restriction on the number of return values
    • It can be zero
    • It can be one or more than one
  • You need to define the data type of the return values
• Body of the function
  • These are the actual business logic statements that process input parameters and then return the values.

Write a function that accepts two integer numbers and returns their sum

Important point about this function

• The function accepts two parameters and the data type of both parameters is integer.
• As sum is returned the data type of the return value will also be an integer.
• We can define the name of the function as add

func add(number1 int, number2 int) (int) {
 // returning the sum of two numbers
 return number1 + number2
}

Write to function to check if the given number is an even number or not

In Golang we have remainder operator (%). If a number is completely divisible by another number then the remainder is zero

package main

import "fmt"

func main() {
	var x int = 10
	value := checkIsEven(x)

	fmt.Println(value)
}

// function to check if the number is event or not
// accepts integer parameter
// returns bool value
func checkIsEven(n int) bool {
	// using remainder operator to check if number is completely divisible by 2
	if n%2 == 0 {
		return true
	}
	return false
}

➜  go run main.go
true

Write a function that returns two values

As we know in Golang a function can return zero or one or more than one value. Let’s take a function that accepts an array of integers and returns the smallest and highest value of the array

package main

import (
	"fmt"
	"math"
)

func main() {
	var numbers = []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
	var lowest, highest = findHighestAndLowest(numbers)
	fmt.Println("The highest number is", highest)
	fmt.Println("The lowest number is", lowest)
}

func findHighestAndLowest(numbers []int) (lowest int, highest int) {
	var lowestNumber int = math.MaxInt
	var highestNumber int = math.MinInt
	for _, number := range numbers {
		if number < lowestNumber {
			lowestNumber = number
		}
		if number > highestNumber {
			highestNumber = number
		}
	}
	return lowestNumber, highestNumber
}

➜  go run main.go
The highest number is 10
The lowest number is 1

• findHighestAndLowest Function explanation
  • It accepts an integer array and returns two values the lowest and the highest number present in the array
  • Using math, we predefined the lowest number as the highest value any integer variable can take math.MaxInt
    • If the array contains any number then it will be lower than the highest value that an integer can take
  • Using math, we predefined the highest number as the lowest value any integer variable can take math.MinInt
    • If the array contains any number then it will be higher than the lowest value that an integer can take
  • We check with every number that is present in the array and update the lowestNumber and highestNumber variable
  • Finally, we return two values

References

• YouTube Channel
• Kafka Consumer in Python