C # Value types and reference types

Data has value types and reference types, and we usually call constants of reference types as instances

One, the constant storage location is different:
The value type constant is in the stack, and the instance is in the managed heap.

The corresponding relationship between variables and constants is different:
The independence of a value type variable: the constant itself is stored in the variable's own storage space, and a variable corresponds to a constant.
A many-to-one relationship between a reference type variable and an instance: The variable only holds the address where the constant is, and the same instance can be referenced by multiple variables.

Three, the internal operation is different when initializing variables:

1. Initialize value type variables
When a value type variable is assigned a value, the constant is copied and placed in the variable.

2. Initializing reference variables
When assigning a value to a reference type variable, the address of the instance is stored in the variable.
3. Packing
If a value type constant is used to assign a value to a reference type variable, the CLR attempts to wrap an instance based on that constant, and then place the instance address in a variable.

int a=5; Object o=a; // boxed, according to 5 is wrapped a reference type constant, with O to save the object address. 

Summary: For the sake of efficiency, the integral type, float type These common types are set to the value type.
However, some CLR functions only accept reference type parameters, so there are boxing and unboxing to wrap the operand type constants into the corresponding reference types to facilitate manipulation.

C # Value types and reference types