Can string be null in C#?
Article: https://net-programmers.com/Articles/...
In this article we're going to answer the question whether string can be null in C#.
Value vs reference types
The first thing that we need to understand is the difference between value and reference types.
Value types are used to directly represent a value and are stored on the stack for quick access.
They are usually small and lightweight.
Examples: byte, short, int, long.
Value types cannot be null.
Reference types are types with content placed on the heap and the stack contains only a reference to them.
Examples: string, object
They're usually more complex than the value types.
Reference types can be null.
Since string is a reference type it can be null.
Nullable types
Since inserting null into a value type is impossible by default it was necessary to create nullable types to enable this type of behaviour.
You can use the question mark operator to create a nullable type out of a value type.
int to int?
You can also create a nullable type out of a reference type.
string to string?
It gives the IDE context information indicating that this given type is expected to contain null values.
You can use the null-forgiving operator (exclamation mark !) to signal to the IDE that a given variable of nullable type won't cotain null in a given scenario. It is usefull to prevent automatic warnings from the IDE.
Here is a small example using both null-forgiving operator and nullable types.