Main and init functions in Golang

Go language has reserved two special purpose functions and those functions are main() and init() . Here are the things to know about using main() and init() functions in Golang .

Main and init functions in Golang

main() function

In Go, the main package is a special package used with executable programs and this package contains the main() function . The main() function is a special type of function and is the entry point for executable programs. It does not take any arguments and does not return anything. Go automatically calls the main() function, so there is no need to call the main() function directly and every executable program must contain a main package and a unique main() function.

For example:

// Chương trình Go minh họa
// khái niệm của hàm main() 

// Khai báo gói chính
package main

// Nhập các gói
import (
    "fmt"
    "sort"
    "strings"
    "time"
)

// Hàm chính
func main() {

    // Sắp xếp slice đưa ra
    s := []int{345, 78, 123, 10, 76, 2, 567, 5}
    sort.Ints(s)
    fmt.Println("Sorted slice: ", s)

    // Tìm chỉ mục
    fmt.Println("Index value: ", strings.Index("Quantrimang", "ks"))

    // Tìm thời gian
    fmt.Println("Time: ", time.Now().Unix())

}

Result:

Sorted slice:  [2 5 10 76 78 123 345 567]
Index value:  3
Time:  1257894000

init() function

The init() function is just like the main function, it does not take any arguments and does not return anything. It is present in every package and is called when the package is initialized. It is implicitly declared, so you cannot reference it from anywhere and you are allowed to create multiple init() functions in the same program and they are executed in the order they are created. You are allowed to create init() functions anywhere in the program and they are called in the order of the dictionary file name (Alphabetical order). You are allowed to put statements if there is an init() function, but always remember that the init() function is executed before the main() function call, so it is independent of the main() function. The main purpose of the init() function is to initialize global variables that cannot be initialized in the global context.

For example:

// Chương trình Go minh họa
// khái niệm của hàm init() 

// Khai báo gói chính
package main

// Nhập gói
import "fmt"

// Hàm init() có nhiều nhánh
func init() {
    fmt.Println("Welcome to init() function")
}

func init() {
    fmt.Println("Hello! init() function")
}

// Hàm chính
func main() {
    fmt.Println("Welcome to main() function")
}

Result:

Welcome to init() function
Hello! init() function
Welcome to main() function
Sign up and earn $1000 a day ⋙

Leave a Comment

How to use constants in Golang

How to use constants in Golang

What is a Constant or Const in Golang? Here's what you need to know about using constants in Go.

Volatile functions in Golang

Volatile functions in Golang

Variadic functions in Go allow you to pass a variable number of arguments to a function. Here's everything you need to know about variadic functions in Golang.

Named return parameters in Golang

Named return parameters in Golang

In Golang, named return parameters are often referred to as named parameters. Golang allows naming the return parameters or results of functions in the function signature or definition.

Keywords in Go

Keywords in Go

Keyword - Keywords are words in a language that are used for some internal processes or represent some predefined actions. Here is what you need to know about keywords in Golang.

Data types in Golang

Data types in Golang

Data types specify what type of data a valid Go variable can hold. In the Go language, types are divided into four categories as follows:

Function arguments in Golang

Function arguments in Golang

Go supports two main ways to pass arguments: Pass by Value and Pass by Reference. Go uses pass by value by default.

Function returning multiple values ​​in Golang

Function returning multiple values ​​in Golang

In Go language, you are allowed to return multiple values ​​from a function, using the return statement. In other words, in a function, a return statement can return multiple values.

Switch Statement in Go

Switch Statement in Go

Golang like most other programming languages ​​has switch statement. Here is how to use switch statement in Golang.

Cases to know when using selection statements in Golang

Cases to know when using selection statements in Golang

In this article, we will learn how to use default case to avoid deadlock. But first, we will learn what is deadlock case when using select command in Golang?

Anonymous structures and fields in Golang

Anonymous structures and fields in Golang

Anonymous structs in Golang are temporary structures with no names used for one-time purposes, while anonymous fields allow embedding of unnamed fields.

How to use Rune in Golang

How to use Rune in Golang

What is Rune in Golang? How to use Rune in Golang? This article will give you the answer.

How to use operators in Golang

How to use operators in Golang

Operators allow us to perform different types of operations on operands. In Go language, operators can be classified based on their different functions.

Void identifier in Golang

Void identifier in Golang

_(underscore) in Golang is called Blank Identifier. Identifier is a user-defined name of program elements used for identification purposes.

How to create basic program in Golang

How to create basic program in Golang

Hello, World! is the first basic program in any programming language. You can write this first program in Golang by following the steps below.

How to Install Go on Windows

How to Install Go on Windows

Golang can be easily installed on Windows. Here is a step-by-step guide to install Golang on Windows.

Top 5 best automatic home coffee makers

Top 5 best automatic home coffee makers

The automatic home coffee maker is a modern and professional product, bringing you and your family delicious cups of coffee with just a few quick steps.

Difference between regular TV and Smart TV

Difference between regular TV and Smart TV

Smart TVs have really taken the world by storm. With so many great features and the ability to connect to the Internet, technology has changed the way we watch TV.

Why doesnt the freezer have a light but the refrigerator does?

Why doesnt the freezer have a light but the refrigerator does?

Refrigerators are familiar appliances in families. Refrigerators usually have 2 compartments, the cool compartment is spacious and has a light that automatically turns on every time the user opens it, while the freezer compartment is narrow and has no light.

2 Ways to Fix Network Congestion That Slows Down Wi-Fi

2 Ways to Fix Network Congestion That Slows Down Wi-Fi

Wi-Fi networks are affected by many factors beyond routers, bandwidth, and interference, but there are some smart ways to boost your network.

How to Downgrade from iOS 17 to iOS 16 without Losing Data using Tenorshare Reiboot

How to Downgrade from iOS 17 to iOS 16 without Losing Data using Tenorshare Reiboot

If you want to go back to stable iOS 16 on your phone, here is the basic guide to uninstall iOS 17 and downgrade from iOS 17 to 16.

What happens to the body when you eat yogurt every day?

What happens to the body when you eat yogurt every day?

Yogurt is a great food. Is it good to eat yogurt every day? What will happen to your body when you eat yogurt every day? Let's find out together!

Which type of rice is best for health?

Which type of rice is best for health?

This article discusses the most nutritious types of rice and how to maximize the health benefits of whichever rice you choose.

How to wake up on time in the morning

How to wake up on time in the morning

Establishing a sleep schedule and bedtime routine, changing your alarm clock, and adjusting your diet are some of the measures that can help you sleep better and wake up on time in the morning.

Rent Please! Landlord Sim Tips for Beginners

Rent Please! Landlord Sim Tips for Beginners

Rent Please! Landlord Sim is a simulation mobile game on iOS and Android. You will play as a landlord of an apartment complex and start renting out an apartment with the goal of upgrading the interior of your apartments and getting them ready for rent.

Latest Bathroom Tower Defense Codes and How to Enter Codes

Latest Bathroom Tower Defense Codes and How to Enter Codes

Get Bathroom Tower Defense Roblox game codes and redeem them for exciting rewards. They will help you upgrade or unlock towers with higher damage.

Structure, symbols and operating principles of transformers

Structure, symbols and operating principles of transformers

Let's learn about the structure, symbols and operating principles of transformers in the most accurate way.

4 Ways AI Is Making Smart TVs Better

4 Ways AI Is Making Smart TVs Better

From better picture and sound quality to voice control and more, these AI-powered features are making smart TVs so much better!

Why ChatGPT is better than DeepSeek

Why ChatGPT is better than DeepSeek

DeepSeek initially had high hopes. As an AI chatbot marketed as a strong competitor to ChatGPT, it promised intelligent conversational capabilities and experiences.

Meet Fireflies.ai: The Free AI Secretary That Saves You Hours of Work

Meet Fireflies.ai: The Free AI Secretary That Saves You Hours of Work

It's easy to miss important details when you're jotting down other essentials, and trying to take notes while chatting can be distracting. Fireflies.ai is the solution.

How to raise Axolotl Minecraft, tame Minecraft Salamander

How to raise Axolotl Minecraft, tame Minecraft Salamander

Axolot Minecraft will be a great assistant for players when operating underwater if they know how to use them.