Logical Pattern in C#: What It Is and How to Use It

In C#, a logical pattern combines multiple patterns using logical operators like and, or, and not to create complex matching conditions in switch expressions or is expressions. It helps check if a value fits multiple criteria at once in a clear and readable way.

How It Works

Think of a logical pattern as a way to combine simple yes/no questions about a value into a bigger question. For example, you might want to check if a number is both even and greater than 10. Instead of writing separate checks, a logical pattern lets you combine these checks into one.

In C#, logical patterns use keywords like and, or, and not to join smaller patterns. This is like using "and", "or", and "not" in everyday language to make complex decisions. The program tests the value against these combined rules and tells you if it matches.

Example

This example shows how to use logical patterns in a switch expression to classify a number based on multiple conditions.

csharp

int number = 15;
string result = number switch
{
    > 10 and < 20 => "Between 11 and 19",
    <= 0 => "Zero or Negative",
    _ => "Other"
};
Console.WriteLine(result);

Output

Between 11 and 19

When to Use

Use logical patterns when you want to check if a value meets multiple conditions at once in a clean and readable way. They are especially helpful in switch expressions or is checks where you want to combine simple tests like ranges, types, or equality.

For example, you might use logical patterns to validate user input, filter data, or handle different cases in your program based on complex rules without writing many nested if statements.

Key Points

• Logical patterns combine multiple patterns using and, or, and not.
• They make complex condition checks easier to read and write.
• Supported in C# 9.0 and later versions.
• Commonly used in switch expressions and is pattern matching.

Key Takeaways

Logical patterns combine simple checks into complex conditions using and, or, and not.

They improve code readability and reduce nested if statements.

Use them in switch expressions and is pattern matching for clear condition handling.

Logical patterns require C# 9.0 or newer.

They help write concise and expressive code for multiple condition checks.