2_A

The Types

The types in .NET Framework can be of value type or reference type [1]. A value type holds the data within its own memory allocation and a reference type contains a pointer to another memory location that holds the real data. Reference type variables are stored in the heap while value type variables are stored in the stack.

Memory allocation [1]:

Value Types

A value type stores its contents in memory allocated on the stack [1-4]. When a value type is created, a single space in memory is allocated to store the value and that variable directly holds a value. When assigning it to another variable, the value is copied directly and both variables work independently.

The following data types are all of value type [1-4]:

bool
byte
char
decimal
double
enum
float
int
long
sbyte
short
struct
uint
ulong
ushort

Reference Types

Reference types are used by a reference which holds a reference (address) to the object but not the object itself [1-4]. Because reference types represent the address of the variable rather than the data itself, assigning a reference variable to another doesn't copy the data. Instead it creates a second copy of the reference, which refers to the same location of the heap as the original value. Reference type variables are stored in a different area of memory called the heap. This means that when a reference type variable is no longer used, it can be marked for garbage collection.