Difference in C# between different getter styles

Question

I do sometimes see abbreviations in properties for the getter. E.g. those two types:

public int Number { get; } = 0

public int Number => 0;

Answer 1

These are C# 6 language features.

First example

public int Number { get; } = 0

The first example is a getter-only auto property. The backing field of a getter-only auto-property is implicitly declared as readonly.

Second example

public int Number => 0;

And the second example is expression bodies on property-like function members. Note that there isn't any get keyword: It is implied by the use of the expression body syntax.

Both are readonly.