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Exercise: Browser History Navigation

Implement a class-based browser navigation system using stacks to manage visiting, returning to, and going forward to web pages.

Problem statement

Real web browsers use Last-In-First-Out (LIFO) data structures to handle navigation. When you visit a new page, the previous page is saved to your history. When you click “Back”, the current page is saved to a “Forward” list, and the previous page is loaded. You will build a complete utility class that encapsulates this exact logic.

Task requirements

  • Create a Browser class inside a defined namespace.

  • Maintain the CurrentPage, a back history, and a forward history within the class.

  • Implement a Visit(string url) method that saves the current page to the back history, updates the current page, and clears the forward history.

  • Implement a Back() method that saves the current page to the forward history, retrieves the most recent page from the back history, and sets it as the current page.

  • Implement a Forward() method that saves the current page to the back history, retrieves the most recent page from the forward history, and sets it as the current page.

Constraints

  • You must use two generic Stack<string> collections: one for the back history and one for the forward history.

  • Use the Push() method to add pages to the stacks.

  • Use the Pop() method to retrieve and remove pages from the stacks.

  • Use the Count property to check if a stack has items before attempting to pop.

Good luck trying the exercise! If you’re unsure how to proceed, check the “Solution” tab above.

Get hints

  • Remember that a Stack<T> operates on a Last-In-First-Out (LIFO) principle, meaning the last item you Push will be the first one you Pop.

  • Remember that visiting a brand new page always invalidates the ability to go “Forward”. You can use the Clear() method on your forward stack when Visit() is called.

  • Before calling Pop(), always wrap your logic in an if (_myStack.Count > 0) check to prevent runtime errors when the user clicks back or forward too many times.

  • When moving backward, the current page must be pushed to the forward stack before you overwrite the CurrentPage variable with the popped value.

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Home
Courses
Learn C# Fundamentals

Exercise: Browser History Navigation

Implement a class-based browser navigation system using stacks to manage visiting, returning to, and going forward to web pages.

Problem statement

Real web browsers use Last-In-First-Out (LIFO) data structures to handle navigation. When you visit a new page, the previous page is saved to your history. When you click “Back”, the current page is saved to a “Forward” list, and the previous page is loaded. You will build a complete utility class that encapsulates this exact logic.

Task requirements

  • Create a Browser class inside a defined namespace.

  • Maintain the CurrentPage, a back history, and a forward history within the class.

  • Implement a Visit(string url) method that saves the current page to the back history, updates the current page, and clears the forward history.

  • Implement a Back() method that saves the current page to the forward history, retrieves the most recent page from the back history, and sets it as the current page.

  • Implement a Forward() method that saves the current page to the back history, retrieves the most recent page from the forward history, and sets it as the current page.

Constraints

  • You must use two generic Stack<string> collections: one for the back history and one for the forward history.

  • Use the Push() method to add pages to the stacks.

  • Use the Pop() method to retrieve and remove pages from the stacks.

  • Use the Count property to check if a stack has items before attempting to pop.

Good luck trying the exercise! If you’re unsure how to proceed, check the “Solution” tab above.

Get hints

  • Remember that a Stack<T> operates on a Last-In-First-Out (LIFO) principle, meaning the last item you Push will be the first one you Pop.

  • Remember that visiting a brand new page always invalidates the ability to go “Forward”. You can use the Clear() method on your forward stack when Visit() is called.

  • Before calling Pop(), always wrap your logic in an if (_myStack.Count > 0) check to prevent runtime errors when the user clicks back or forward too many times.

  • When moving backward, the current page must be pushed to the forward stack before you overwrite the CurrentPage variable with the popped value.

Similar Problems
ObservableCollection
IEnumerable Interface
Sets and Performance Complexity
Immutable Collections
Quiz Yourself: Collections
Exercise: Product Price Lookup
Exercise: The Unique Tag Cleaner
Generic List
Stacks and Queues
Dictionary
C# 14.0
namespace Navigation;
using System.Collections.Generic;
public class Browser
{
    // 1. Initialize two stacks for back and forward history
    
    public string CurrentPage { get; private set; } = "Blank Page";
    public void Visit(string url)
    {
        // 2. Implement Visit logic
        // - Push CurrentPage to back stack
        // - Update CurrentPage
        // - Clear forward stack
    }
    public void Back()
    {
        // 3. Implement Back logic
        // - Check if back stack has items
        // - Push CurrentPage to forward stack
        // - Pop from back stack and set as CurrentPage
    }
    public void Forward()
    {
        // 4. Implement Forward logic
        // - Check if forward stack has items
        // - Push CurrentPage to back stack
        // - Pop from forward stack and set as CurrentPage
    }
}