Skip to content
BankyBluePrints.com

C# Feature - Constant patterns

Overview

Section titled “Overview”

Constant patterns let you match against literal values or named constants with the is operator or inside switch expressions.

Introduced In

Section titled “Introduced In”

C# 7.0 (2017)

Before

Section titled “Before”
if (status == "Ready")
{
  Start();
}

After

Section titled “After”
if (status is "Ready")
{
  Start();
}

Annotated Example

Section titled “Annotated Example”
string message = responseCode switch
{
  200 => "OK",
  404 => "Missing",
  _ => "Other"
};

Gotchas & Best Practices

Section titled “Gotchas & Best Practices”
  • Prefer constant patterns inside broader pattern matching code to keep style consistent.
  • Use the discard pattern _ for the fallback branch.
Section titled “Related Features”

Version Notes

Section titled “Version Notes”
  • C# 7 introduced constant and type patterns.