Your First Go Program

In this tutorial, we’ll break down a basic "Hello, World" program in Go, explaining each component step by step.

Package Declaration

The program begins with the package declaration:

package main

This line defines the package name. In Go, every program starts with a package declaration. Packages help organize and reuse code. When building standalone executable programs, the special package "main" is used to indicate the entry point.

Import Statement

Next is the import statement:

import "fmt"

The import keyword brings code from external packages into your program. Here, the "fmt" package is imported, which provides input and output formatting functions. Note that the package name is enclosed in double quotes, which is the correct syntax in Go.

Comments

Comments are essential for documenting your code. They are ignored during compilation. In Go, comments can be written in two ways:

Single-Line Comments

// This is a single line comment.

Single-line comments start with two forward slashes (//). They are ideal for brief explanations.

Multi-Line Comments

/* This is a multi-line comment. */

Multi-line comments are enclosed within /* and */ and are useful for longer explanations.

Function Declaration

The next part of the program is the function declaration:

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

Here’s what happens:

1. Entry Point: The main function is the entry point of a Go program. When the program runs, the main function is executed automatically.
2. Function Body: The statements within the curly braces { } define what happens when the program starts.

Inside the Main Function

Within the main function, we have:

fmt.Println("Hello, World")

This statement has three main elements:

1. Package Name: fmt is the package that provides the necessary functionalities for formatted I/O.
2. Function Name: Println is a function within the fmt package. It prints its argument to the console and adds a newline at the end.
3. Argument: "Hello, World" is the string that is passed to the Println function for output.

When executed, this statement prints "Hello, World" to the console.

Complete Code Example

Below is the complete code snippet with proper syntax highlighting:

package main

import "fmt"

// This is a single line comment.
// Comments are used to explain the code and are ignored by the compiler.

func main() {
    /*
    This is a multi-line comment.
    Multi-line comments span several lines.
    */
    fmt.Println("Hello, World")
}

In summary, this article covered the essential parts of a basic Go program: the package declaration, the import statement, single-line and multi-line comments, and the main function that serves as the starting point of the program.

Let's proceed to get some hands-on practice and explore more advanced features of Go!