C# Feature - default literal

Overview

The default literal allows default to stand on its own when the target type is already known from context.

Introduced In

C# 7.1 (2017)

Before

CancellationToken token = default(CancellationToken);

After

CancellationToken token = default;

Annotated Example

public void Reset(Span<int> buffer)
{
  for (int i = 0; i < buffer.Length; i++)
  {
    buffer[i] = default;
  }
}

Gotchas & Best Practices

• Use default(T) when the target type is not obvious to the reader.
• The literal works best in assignments, returns, and optional arguments with clear typing.

Related Features

• Target-typed new
• Nullable value types

Version Notes

• C# 7.1 introduced the default literal to reduce repetition.