Functions

Functions provide a way to divide your code into logical blocks and reuse them minimising the time and effort and improve the managability of the code.

Functions in Go

Functions in golang are defined using the func keyword.

The syntax to define a function in go

func <name of the function> (<inputs to the function>) (<datatypes of return values from the function>) {
    // your code here
}

Let's write a add function using this syntax

func add (a int, b int) int {
    return a + b
}

How to call a function in your code

Calling a function is as easy as writing the function name and giving it the arguments. Now for an example let's call our add function in the main method.

package main

import "fmt"

func main() {
    sum := add(3, 5)

    fmt.Println(sum)        // prints 8
}

Go also let's you ignore specific fields in the return values using the _ variable.

package main

import "fmt"

func sumAndDiff (a int, b int) (int, int) {
    return a + b, a - b
}

func main() {
    sum, _ := sumAndDiff(5, 3)      // the 2nd variable is ignored and not used

    fmt.Println(sum)                // prints 8
}

We can also add named return values so that we dont need to deliberately return something in the function. But beware, use this only in small functions.

package main

import "fmt"

func add (a int, b int) (sum int) {         // here we are defining the variable name of what we are returning
    sum = a + b                             // so no need for a return statement, go takes care of it
}

func main() {
    sum := add(3, 5)

    fmt.Println(sum)                // prints 8
}

Exercise

In this exercise, your will be given a integer slice as a input. Write a function with name sumAll that loops through all the numbers in the slice and returns the sum of the numbers.