Why struct is value type in c

Structs can be instantiated without using a new operator. A struct cannot inherit from another struct or class, and it cannot be the base of a class. All structs inherit directly from System. ValueType, which inherits from System. Struct cannot be a base class.

So, Struct types cannot abstract and are always implicitly sealed. Abstract and sealed modifiers are not allowed and struct member cannot be protected or protected internals. Function members in a struct cannot be abstract or virtual, and the override modifier is allowed only to the override methods inherited from System.

Null means not refering to any object. A value type variable cannot be null because it holds value, not a memory address. C ASP. Skill Tests ASP. All the value types derive from System. ValueType , which in-turn, derives from System.

Example: Passing Value Type Variables. WriteLine i ; ChangeValue i ; Console. Try it. Example: Passing Reference Type Variable. WriteLine std1. Example: Passing String.

That is, a variable of a class type contains a reference to an instance of the type, not the instance itself. Because structure types have value semantics, we recommend you to define immutable structure types.

Beginning with C 7. All data members of a readonly struct must be read-only as follows:. That guarantees that no member of a readonly struct modifies the state of the struct. In a readonly struct, a data member of a mutable reference type still can mutate its own state. The following code defines a readonly struct with init-only property setters, available in C 9.

Beginning with C 8. If you can't declare the whole structure type as readonly , use the readonly modifier to mark the instance members that don't modify the state of the struct. Within a readonly instance member, you can't assign to structure's instance fields.

However, a readonly member can call a non- readonly member. In that case the compiler creates a copy of the structure instance and calls the non- readonly member on that copy. As a result, the original structure instance is not modified. Typically, you apply the readonly modifier to the following kinds of instance members:. You can also apply the readonly modifier to methods that override methods declared in System. Object :. If you need to apply the readonly modifier to both accessors of a property or indexer, apply it in the declaration of the property or indexer.

The compiler declares a get accessor of an auto-implemented property as readonly , regardless of presence of the readonly modifier in a property declaration. The compiler may make use of the readonly modifier for performance optimizations. For more information, see Write safe and efficient C code. Beginning with C 10, you can use the with expression if you need to mutate immutable properties or fields of a structure-type instance. A with expression makes a copy of its operand with specified properties and fields modified.

You use object initializer syntax to specify what members to modify and their new values, as the following example shows:. When you design a structure type, you have the same capabilities as with a class type, with the following exceptions:.

You can't declare a parameterless constructor. When you create a struct object using the new operator, it gets created and the appropriate constructor is called. Unlike classes, structs can be instantiated without using the new operator. If you do not use new, the fields will remain unassigned and the object cannot be used until all of the fields are initialized. You can "new" an integer as well.

The difference is you CANT pass a reference class by value. It says right here in the MSDN document, the new operator is used to invoke the default constructor of a value type. You don't have to use the new operator to create a struct. If you do it will call its constructor, if you don't all field will remain unassigned.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. If a struct is a value type why can I new it? Asked 8 years, 7 months ago.