The 5 Different Meanings of the Question Mark in C#

In C# the question mark has 5 meanings as of C# 8.

1. Ternary operators

(true ? "true": "false")

2. Null conditional operator

items?.Count()

3. Nullable types (this should be rebranded as nullable value types)

int?

4. Null-coalescing operator

isnull ?? string.Empty

5. Nullable reference types

string?