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Go: Hello World!

Overview

We will write our first go program "Hello, World!".

Prerequisites

Before starting, ensure you have:

  • Go installed on your system
  • A text editor or IDE
  • Basic understanding of using the terminal

Checking Your Go Installation

First, verify that Go is properly installed on your system by running this command in your terminal:

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go version

You should see output similar to this:

Terminal Output
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#$ go version 
go1.25.1 X:nodwarf5 linux/amd64

Not Installed?

If you see a "command not found" error, you'll need to download and install Go first.

If not, for now, you can visit Go Playground

Writing Your First Go Program

Let's create a simple program that prints "Hello, World!" to the console.

Assumption: You are using Linux, Mac, or WSL.

Open a directory of your choice in your terminal and Create a new file named hello.go in your preferred directory. If you are on linux you can type touch hello.go in your terminal.

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cd /home/user/Downloads/program/ && touch hello.go

Copy this code into your hello.go file:

hello.go
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package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

Understanding the Code

Breakdown the code:

Code Structure

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package main
  • Every Go program starts with a package declaration
  • main package creates an executable program
  • Other packages create reusable libraries
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import "fmt"
  • Imports the formatting package fmt. It Provides functions for i/o operation.
  • Essential for console interaction.
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func main() {
    fmt.Println("Hello, World!")
}
  • Function declaration using func keyword.
  • Entry point of the program
  • fmt.Println() prints text and adds a newline
  • Program execution starts here

Extra Jargon: If you have noticed in the program, the line fmt.Println("Hello, World!"), you may wonder why the Println function p is in caps. This is because Println is a function from the fmt package that is used to print text to the console. The fmt package is part of the Go standard library and provides functions for formatted I/O.

The Println function is one of the most commonly used functions in the fmt package. It stands for "Print Line" and is used to print text to the console with a newline at the end. The Println function is case-sensitive and must be written in caps for the first letter, that way the Go compiler knows that you are referring to the Println function from the fmt package.

Running our Program

There are two ways to run your Go program.

Use go run to compile and execute in one step:

Terminal
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go run hello.go

Output
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Hello, World!

Quick Development

This method is perfect for development and testing as it's faster for quick iterations.

First, compile the program:

Terminal
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go build hello.go

Then run the executable:

Terminal - Linux/macOS
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./hello
Terminal - Windows
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hello.exe

Production Use

Second method, when we build the file, we are creating an executable file that we can distribute and run on any system without Go installed.

Go provides several ways to output text. Here are some variations of our Hello World program:

Print Variations

hello.go
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package main

import "fmt"

func main() {
    fmt.Printf("Hello, World!\n")  // Formatted print
}

Tip

Printf allows formatted strings using placeholders like %s, %d, etc.

hello.go
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package main

import "fmt"

func main() {
    fmt.Print("Hello, ")     // Prints without newline
    fmt.Println("World!")    // Prints with newline
}

Tip

Combine Print and Println for flexible output formatting.

What's Next?

Congratulations!

We've successfully written and run our first Go program! Here's what we've learned:

  • Setting up Go
  • Creating a Go source file
  • Understanding basic Go syntax
  • Running Go programs
  • Using different print functions

Next Steps

Continue learning:

  • Go to the compiler section to learn more about the Go compiler.