Structs vs. Classes in C#: When Should You Choose Which?

When will the structure (struct) and the class (class)

In C#, when selecting the structure or class, please consider the following principles:

When to use the structure:

This type represents a single value, similar to basic types (for example, integer and dual -precision floating point number).

The size of the example is less than 16 bytes.
It is the same (it cannot be changed after creation).
It will not be boxed frequently (converted to a reference type).
• When to use the class:

This type represents multiple or complex data structures.

The size is greater than 16 bytes.

• It needs to be modified after creation.
• It will frequently pack or pass as a reference parameter.
Microsoft's position

Microsoft recommends that the structure is used for small, usually a short example, or those instances embedded in other objects. However, they also warn that unless they meet all the above characteristics, do not define the structure.

Example

.NET Framework's

class uses the internal structure as its

and type. These structures follow the above principles because they:

indicates a single value (key value pair and enumerator state). Dictionary<TKey, TValue> Entry very small (less than 16 bytes). Enumerator

is the same (after the creation, their data cannot be changed).

• Avoid frequent packing (they are mainly used in internal).
When will Microsoft break the rules
• Despite these guidance principles, Microsoft's internal structures often violate the size and invariance rules. This is to give priority to speed and efficiency, because the instance of the structure and the speed ratio ratio is faster. However, these exceptions should be handled to avoid accidents.

Other precautions

When the structure is implemented, it will be a reference type when it is converted to the interface.

Should deal with the type of value responsible to avoid accidental copying or modification.

The performance advantages of Structure are mainly reflected in the scenario involving a large number of or frequent creation and access to small data items.

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