What The `for` Loop Explained

Part of the Fundamentals section of Coddy's GO journey — lesson 44 of 109.

The for loop is Go's only looping construct, used to repeat a block of code multiple times. Let's explore how it works step by step.

First, let's create a simple program that counts from 1 to 5 using a for loop:

for i := 1; i <= 5; i++ {
    fmt.Println(i)
}

After executing this code, the numbers 1 through 5 will show on the screen, one per line:

Let's understand what's happening in our for loop:

The for loop has three main parts:

1. i := 1 - This is the initialization part where we create a variable and set its starting value

2. i <= 5 - This is the condition that's checked before each loop iteration; the loop continues as long as this is true

3. i++ - This is the post statement that runs after each loop iteration (it adds 1 to i)

The loop works by first initializing i to 1, then checking if i is less or equal to 5. If true, it runs the code inside the loop (printing the value), then executes i++ to increase the value by 1. This process repeats until the condition becomes false (when i becomes 6).

Challenge

Beginner

In this challenge, you'll practice using a basic for loop to count and print numbers.

Your task is to write a for loop that counts from 1 to 10 and prints each number on a new line.

This will help you understand how to use the for loop for simple counting tasks.

Cheat sheet

The for loop is Go's only looping construct, used to repeat a block of code multiple times.

Basic for loop syntax:

for i := 1; i <= 5; i++ {
    fmt.Println(i)
}

The for loop has three main parts:

1. i := 1 - Initialization: creates a variable and sets its starting value

2. i <= 5 - Condition: checked before each iteration; loop continues while true

3. i++ - Post statement: runs after each iteration (increments i by 1)

Try it yourself

package main

import "fmt"

func main() {
	// TODO: Write a for loop that counts from 1 to 10
	// and prints each number on a new line
	
	
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction to Go

What is Go?Hello World Println Go Comments

4Comparison & Logical Operators

Comparison Operators - Part 1 Comparison Operators - Part 2 Logical AND Operator Logical OR Operator Logical NOT Operator Operator Precedence Basics Recap - Making Comparisons

7Control Flow: Loops

What The `for` Loop ExplainedFor Loop - Basic For Loop - Condition Only The `break` Keyword The `continue` Keyword Nested Loops Recap - Repeating Actions

10Composite Types: Arrays

Introduction to Arrays Declaring Arrays Initializing Arrays Accessing Array Elements Array Length with `len`Iterating Over Arrays Multi-dimensional Arrays

13Composite Types: Structs

Defining Custom Types Creating Struct Instances Accessing Struct Fields Pointers to Structs Initializing Structs Embedded Structs Anonymous Structs Recap - Custom Data Structures

2Variables and Basic Data Types

What is a variable Type Inference with `:=`Integers (int)Floating-Point Numbers Booleans Strings Zero Values Constants Naming Conventions Recap - Variables and Types

5Basic Input/Output

Formatted Output Format Verbs Printing Types Getting Basic User Input Recap - Input and Output

8Functions

Understanding Functions Declaring a Function Calling Functions Function Parameters Returning a Single Value Returning Multiple Values Named Return Values Function Scope Basics Recap - Creating Reusable Code

11Composite Types: Slices

Introduction to Slices Declaring Slice Literals Creating Slices with `make`Slice Length vs Capacity Accessing Slice Elements Appending Elements Slicing Existing Slices/Arrays Iterating Over Slices Copying Slices Recap - Dynamic Lists

14Basic Error Handling

The Concept of Errors The `error` Interface Functions Returning Errors Checking for Errors Creating Simple Errors Creating Formatted Errors Basic Error Handling Recap - Handling Problems