1. Introduction

This tutorial aims to give you a clear understanding of how to control the flow of a Go program. We will be focusing on conditional statements (if, if-else, switch) and loops (for, while). By the end of this tutorial, you will be able to write and understand Go programs that feature complex control flow.

You will learn:

• How to use conditional statements.
• How to use loops.
• The concepts behind controlling the flow of programs.

Prerequisites:

• Basic understanding of Go programming language.
• Installed Go environment on your local machine.

2. Step-by-Step Guide

Conditional Statements

In Go, we use conditional statements to make decisions based on certain conditions.

If Statement

The if statement is used to test a condition. If the condition is true, the block of code inside the if statement will be executed.

if condition {
    // code to be executed if condition is true
}

If-Else Statement

The if-else statement is used when you want to perform a different operation in the case where the initial if condition is not met.

if condition {
    // code to be executed if condition is true
} else {
    // code to be executed if condition is false
}

Switch Statement

The switch statement is used to select one of many blocks of code to be executed.

switch condition {
case n:
    // code to be executed if condition = n
default:
    // code to be executed if no case matches
}

Loops

Loops are used when we want to repeat a block of code multiple times.

For Loop

In Go, the for loop is the only loop statement. It can be used in three forms.

• The simple loop

for condition {
    // code to be executed while condition is true
}

• The pre and post statement loop

for initialization; condition; post {
    // code to be executed while condition is true
}

• The infinite loop

for {
    // code to be executed infinitely
}

3. Code Examples

If-Else Statement

package main

import "fmt"

func main() {
    age := 18

    if age >= 18 {
        fmt.Println("You are eligible to vote.")
    } else {
        fmt.Println("You are not eligible to vote.")
    }
}

This code will output "You are eligible to vote." since the age variable is 18, which is greater than or equal to 18.

Switch Statement

package main

import "fmt"

func main() {
    day := "Friday"

    switch day {
    case "Monday":
        fmt.Println("Today is Monday.")
    case "Tuesday":
        fmt.Println("Today is Tuesday.")
    case "Friday":
        fmt.Println("Today is Friday.")
    default:
        fmt.Println("Invalid day.")
    }
}

This code will output "Today is Friday." since the day variable matches the "Friday" case.

For Loop

package main

import "fmt"

func main() {
    for i := 0; i < 5; i++ {
        fmt.Println(i)
    }
}

This code will output the numbers from 0 to 4 in the console.

4. Summary

We have covered how to use conditional statements and loops in Go. You should now feel confident in controlling the flow of a Go program. For further learning, you could try implementing nested if-else statements and nested loops.

5. Practice Exercises

1. Create a Go program that prints out the numbers from 1 to 10 using a for loop.
2. Create a Go program that checks if a number is even or odd using an if-else statement.
3. Create a Go program that prints out the days of the week using a switch statement.

Take your time to work on these exercises. They will help solidify your understanding of control flow in Go. Happy coding!