List patterns in C Sharp (C#) - Mini Project: Build & Apply

List Patterns in C#

📖 Scenario: You are working with a list of daily temperatures recorded over a week. You want to check if the list matches certain patterns to quickly understand the weather trend.

🎯 Goal: Build a C# program that uses list patterns to check if the temperature list starts with a cold day, ends with a hot day, or has a specific pattern in the middle.

📋 What You'll Learn

Create a list of integers called temperatures with exact values

Create a variable called patternToCheck to hold a pattern description

Use list patterns in a switch expression to match temperatures

Print the result of the pattern matching

💡 Why This Matters

🌍 Real World

Checking patterns in lists is useful in many real-world tasks like analyzing sensor data, processing user inputs, or validating sequences.

💼 Career

Understanding list patterns helps in writing clean, readable code for data processing, which is valuable in software development and data analysis jobs.

1

Create the temperature list

Create a list of integers called temperatures with these exact values: 12, 15, 20, 25, 30, 35, 40.

C Sharp (C#)

using System.Collections.Generic;

// Create the list of temperatures
// Your code here

Need a hint?

Use List<int> and initialize it with the exact numbers inside curly braces.

2

Add a pattern description variable

Create a string variable called patternToCheck and set it to an empty string "".

C Sharp (C#)

using System.Collections.Generic;

List temperatures = new() { 12, 15, 20, 25, 30, 35, 40 };

// Create the patternToCheck variable
// Your code here

Need a hint?

Declare a string variable and assign it an empty string.

3

Use list patterns to check the temperatures

Use a switch expression on temperatures to set patternToCheck to:
- "Starts cold" if the first temperature is less than 15,
- "Ends hot" if the last temperature is greater than 35,
- "Warm middle" if the middle three temperatures are between 20 and 30 inclusive,
- Otherwise, set it to "No pattern".
Use list patterns with temperatures in the switch expression.

C Sharp (C#)

using System.Collections.Generic;

List temperatures = new() { 12, 15, 20, 25, 30, 35, 40 };

string patternToCheck = "";

// Use a switch expression with list patterns to set patternToCheck
// Your code here

Need a hint?

Use list patterns with switch and when guards to check the first and last elements, and a pattern for the middle three.

4

Print the pattern result

Write a Console.WriteLine statement to print the value of patternToCheck.

C Sharp (C#)

using System.Collections.Generic;

List temperatures = new() { 12, 15, 20, 25, 30, 35, 40 };

string patternToCheck = temperatures switch
{
    [var first, ..] when first  "Starts cold",
    [.., var last] when last > 35 => "Ends hot",
    [_, _, >= 20 and = 20 and = 20 and  "Warm middle",
    _ => "No pattern"
};

// Print the patternToCheck variable
// Your code here

Need a hint?

Use Console.WriteLine(patternToCheck); to show the result.