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C# Feature - Discards

Overview

Section titled “Overview”

Discards use _ to explicitly ignore values you do not need, which keeps intent clear and avoids placeholder variables.

Introduced In

Section titled “Introduced In”

C# 7.0 (2017)

Before

Section titled “Before”
int parsedValue;
bool ok = int.TryParse(text, out parsedValue);

After

Section titled “After”
bool ok = int.TryParse(text, out _);

Annotated Example

Section titled “Annotated Example”
var (_, month, _) = DateTime.UtcNow;


if (value is not null and not "")
{
  Console.WriteLine(month);
}

Gotchas & Best Practices

Section titled “Gotchas & Best Practices”
  • Use a real variable when the value may become meaningful later in the method.
  • A discard is not a reusable variable; each _ is just an ignored target.
Section titled “Related Features”

Version Notes

Section titled “Version Notes”
  • C# 7 introduced discards for deconstruction, pattern matching, and out arguments.