How to Use Switch Case in C# - Simple Guide

In C#, use the switch statement to select one of many code blocks to execute based on a variable's value. Each case defines a value to match, and break ends the case. The default case runs if no other case matches.

Syntax

The switch statement evaluates a variable and compares it to multiple case values. When a match is found, the code inside that case runs until a break is reached, which exits the switch. The default case runs if no other case matches.

• switch(expression): The variable or expression to check.
• case value: A possible value to match.
• break; Ends the current case.
• default: Runs if no case matches.

csharp

switch (variable)
{
    case value1:
        // code to run if variable == value1
        break;
    case value2:
        // code to run if variable == value2
        break;
    default:
        // code to run if no case matches
        break;
}

Example

This example shows how to use switch to print a message based on a day number.

csharp

using System;

class Program
{
    static void Main()
    {
        int day = 3;

        switch (day)
        {
            case 1:
                Console.WriteLine("Monday");
                break;
            case 2:
                Console.WriteLine("Tuesday");
                break;
            case 3:
                Console.WriteLine("Wednesday");
                break;
            case 4:
                Console.WriteLine("Thursday");
                break;
            case 5:
                Console.WriteLine("Friday");
                break;
            default:
                Console.WriteLine("Weekend");
                break;
        }
    }
}

Output

Wednesday

Common Pitfalls

Common mistakes when using switch include forgetting break; which causes "fall-through" to the next case, and not including a default case which can leave some values unhandled. Also, switch only works with certain types like integers, strings, and enums.

csharp

/* Wrong: Missing break causes fall-through */
switch (value)
{
    case 1:
        Console.WriteLine("One");
        // missing break here causes fall-through
    case 2:
        Console.WriteLine("Two");
        break;
}

/* Correct: Each case ends with break */
switch (value)
{
    case 1:
        Console.WriteLine("One");
        break;
    case 2:
        Console.WriteLine("Two");
        break;
}

Quick Reference

• Use switch to replace multiple if-else when checking one variable.
• Always end cases with break; to avoid running unwanted code.
• Include a default case to handle unexpected values.
• switch supports types like int, string, and enum.

Key Takeaways

Use switch to select code based on a variable's value cleanly.

Always include break; to prevent fall-through between cases.

Add a default case to handle unexpected values.

switch works well with integers, strings, and enums.

Avoid complex logic inside cases; keep them simple and clear.