Breaking from Nested Loops

Part of the Logic & Flow section of Coddy's GO journey. Lesson 2 of 68.

When working with nested loops, a regular break statement only exits the innermost loop. However, Go provides labels that allow you to break out of outer loops directly, giving you precise control over complex loop structures.

A label is an identifier followed by a colon that you place before a loop. You can then use break followed by the label name to exit that specific loop, even from within nested loops.

outer:
for i := 0; i < 3; i++ {
    for j := 0; j < 3; j++ {
        if i == 1 && j == 1 {
            break outer
        }
        fmt.Printf("i=%d, j=%d\n", i, j)
    }
}

In this example, when the condition i == 1 && j == 1 is met, break outer exits both the inner and outer loops immediately. This is particularly useful when searching through 2D data structures where you want to stop searching entirely once you find what you're looking for.

Challenge

Easy

In this challenge, you'll practice using labeled break statements to exit nested loops when searching through a 2D grid. You need to find a specific target number in the grid and stop searching immediately once you find it.

You will receive two inputs:

A string representing the dimensions of the grid in the format "rows,cols" (e.g., "3,4")
A string representing the target number to search for (e.g., "7")

You are provided with the following 2D grid of numbers:

grid := [][]int{
    {1, 2, 3, 4},
    {5, 6, 7, 8},
    {9, 10, 11, 12},
}

Your task is to:

Use the values already read for you in the code above yours: rows and cols (how much of the grid to search), target, and grid
Use nested loops with a labeled break to search through the grid
When you find the target number, print "Found [target] at position ([row], [col])" and immediately exit both loops using the labeled break
If you complete the search without finding the target, print "Target [target] not found"

The position should be reported using 0-based indexing (first row is 0, first column is 0).

Try it yourself

    // TODO: Write your code below
    // Use nested loops with labeled break to search for the target

Test yourself

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

All lessons in Logic & Flow

1Advanced Control Flow

Switch with `fallthrough`Breaking from Nested LoopsContinuing a Specific Loop The `goto` Statement Recap - Advanced Loop Control

4Project: Simple Task List

Project Setup Adding a Task

Viewing All Tasks

Completing a Task

Removing a Task

Putting It All Together

7Error Handling In-Depth

Custom Error Types Wrapping Errors with `%w`Unwrapping with `errors.Is`Unwrapping with `errors.As`Understanding `panic`Using `recover`Recap - Safe Division

10Working with Time

Getting the Current Time Creating a Specific Time Formatting Time Parsing Time Strings Time Duration Time Arithmetic Sleeping and Tickers Recap - Simple Timer

2Structs and Methods

Defining Methods on Structs Value Receivers Pointer Receivers Choosing Receivers Methods vs Functions Recap - Struct Behavior

5Maps In-Depth

Maps of Structs Pointers as Map Values Testing for Nil Maps Comparing Maps Recap - Word Frequency Counter

8Project: Simple Inventory

Project Overview Checking Stock

Adding a New Item

Updating Stock Quantity

Generating a Report

Putting It All Together

11Final Challenges

Basic Contact List Simple Number Validator Unique Item Collector

Practice on your own: Online Go compiler