Category: interview

• sequential collection of chars
• immutable
• max 2GB or about 1 billion characters
• reference type
• are interned – CLR saves memory by maintaining a table, called the “intern pool”, that contains a single reference to each unique literal string declared or created programmatically in your program.

Further read:

https://learn.microsoft.com/en-us/dotnet/api/system.string?view=net-7.0

https://learn.microsoft.com/en-us/dotnet/api/system.string.intern?view=net-6.0#remarks

ref struct type can not be used as object field.

Further read:

`ref struct` types

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/ref-struct

• added as part of C# 7.2.
• defined with ref struct StructName
• always on the stack
• never part of heap
• cannot be element of an array
• cannot be field type of reference type
• can’t implement interfaces
• can’t be boxed
• can’t be type argument
• can’t be captured by closure of lambda or local function
• can’t be used in async methods
• can’t be used in iterators

Further read:

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/ref-struct

Value types are stored in the heap when they are part of the reference type.

Reference types:

• passed via reference
• reside on the heap
• subject to GC
• inherits from System.Object

Value types:

• passed via value
• reside on the stack, CPU registers or the heap
• no subject to GC
• inherits from System.ValueType

Further read:

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/reference-types

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/value-types

https://www.infoworld.com/article/3043992/a-deep-dive-value-and-reference-types-in-net.html