Definition

As in almost all languages, there is a way to encapsulate a set of instructions that performs a specific processing, it is the black box principle, with a set of input parameters and an output result. With the functions one abstracts from the detail of the implementation. It could be written by another person for example.

The term _routine_was also used.

The functions also make it possible to split and identify the different treatments.

Syntax

func <FunctionName>(<Param1> type, <Param2> type, ...) <TypeRetour> {

    // Implémentation
    
}

Example

The most glaring example is the main function of any GO program for the point of entry.

package main

import (
    "fmt"
)

func main() {
    var resultat int = 1
    var monTexte string = "Resultat: " + resultat
    
    fmt.Printf("%vn", monTexte)

}

Important: In terms of the visibility of a function, in this sense we are talking about public or private. This is done by either putting the first letter in lowercase for a private function and a capital letter for a public service.

Function Call

It is all well and good to have declared a function. It is necessary to call on its services. The example below is voluntarily detailed. This function takes an input parameter and returns an output parameter.

package main

import "fmt"

func main() {
    var name string = "John Doe"
    
    messageForYou := message(name)
    fmt.Println(messageForYou)

}

func message(nom string) string {
    return fmt.Sprintf("Hello dear %s.", nom)
}

messageForYou := message(name)

• In summary

  And now you know:

  • Declare functions with input and/or output parameters;

  • Change the scope of the function in private or public which will be highly useful when writing packages for example;

  • Make the call has this function and retrieve its result.