Myc#

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A class type defines

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a data structure that contains data members (fields) and function members (methods, properties, and others). Class types support single inheritance and polymorphism, mechanisms whereby derived classes can extend and specialize base classes.

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A struct type is similar to a class type in that

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it represents a structure with data members and function members. However, unlike classes, structs are value types and do not require heap allocation. Struct types do not support user-specified inheritance, and all struct types implicitly inherit from type object.

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An interface type defines a

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contract as a named set of public function members. A class or struct that implements an interface must provide implementations of the interface’s function members. An interface may inherit from multiple base interfaces, and a class or struct may implement multiple interfaces.

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A delegate type represents references to

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methods with a particular parameter list and return type. Delegates make it possible to treat methods as entities that can be assigned to variables and passed as parameters. Delegates are similar to the concept of function pointers found in some other languages, but unlike function pointers, delegates are object-oriented and type-safe.

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all support generics

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Class, struct, interface and delegate types , whereby they can be parameterized with other types.

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An enum type is a

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distinct type with named constants. Every enum type has an underlying type, which must be one of the eight integral types. The set of values of an enum type is the same as the set of values of the underlying type.

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. Classes support

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inheritance and polymorphism, mechanisms whereby derived classes can extend and specialize base classes.

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Instances of classes are created

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using the new operator, which allocates memory for a new instance, invokes a constructor to initialize the instance, and returns a reference to the instance

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Each member of a class has an associated accessibility, which controls the regions of program text that are able to access the member. There are five possible forms of accessibility.

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Accessibility
Meaning

public
Access not limited

protected
Access limited to this class or classes derived from this class

internal
Access limited to this program

protected internal
Access limited to this program or classes derived from this class

private
Access limited to this class

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Inheritance means that a class implicitly contains all members of its base class, except for

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the instance and static constructors, and the destructors of the base class.

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A static field identifies exactly one storage location.

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No matter how many instances of a class are created, there is only ever one copy of a static field.

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The signature of a method consists of

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the name of the method, the number of type parameters and the number, modifiers, and types of its parameters. The signature of a method does not include the return type.

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There are four kinds of parameters

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value parameters, reference parameters, output parameters, and parameter arrays.

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A value parameter is used for

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input parameter passing. A value parameter corresponds to a local variable that gets its initial value from the argument that was passed for the parameter. Modifications to a value parameter do not affect the argument that was passed for the parameter.

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Value parameters can be

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optional, by specifying a default value so that corresponding arguments can be omitted.

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A reference parameter is used for

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both input and output parameter passing. The argument passed for a reference parameter must be a variable, and during execution of the method, the reference parameter represents the same storage location as the argument variable. A reference parameter is declared with the ref modifier.

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An output parameter is used for

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output parameter passing. An output parameter is similar to a reference parameter except that the initial value of the caller-provided argument is unimportant. An output parameter is declared with the out modifier.

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A parameter array permits

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a variable number of arguments to be passed to a method. A parameter array is declared with the params modifier. Only the last parameter of a method can be a parameter array, and the type of a parameter array must be a single-dimensional array type.

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A virtual method can be

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overridden in a derived class. When an instance method declaration includes an override modifier, the method overrides an inherited virtual method with the same signature. Whereas a virtual method declaration introduces a new method, an override method declaration specializes an existing inherited virtual method by providing a new implementation of that method.

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An abstract method is a

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virtual method with no implementation. An abstract method is declared with the abstract modifier and is permitted only in a class that is also declared abstract. An abstract method must be overridden in every non-abstract derived class.

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Method overloading permits

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multiple methods in the same class to have the same name as long as they have unique signatures. When compiling an invocation of an overloaded method, the compiler uses overload resolution to determine the specific method to invoke. Overload resolution finds the one method that best matches the arguments or reports an error if no single best match can be found.