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The cast operator is not overloadable, but one can write a conversion operator method which lives in the target class. Conversion methods can define two varieties of operators, implicit and explicit conversion operators. The implicit operator will cast without specifying with the cast operator (()) and the explicit operator requires it to be used.
In the C family of languages and ALGOL 68, the word cast typically refers to an explicit type conversion (as opposed to an implicit conversion), causing some ambiguity about whether this is a re-interpretation of a bit-pattern or a real data representation conversion. More important is the multitude of ways and rules that apply to what data ...
In class-based programming, downcasting, or type refinement, is the act of casting a base or parent class reference, to a more restricted derived class reference. [1] This is only allowable if the object is already an instance of the derived class, and so this conversion is inherently fallible.
Safer casting operators, such as dynamic cast that performs run-time type checking. C++11 strongly-typed enumerations cannot be implicitly converted to or from integers or other enumeration types. C++ explicit constructors and C++11 explicit conversion operators prevent implicit type conversions.
Whereas the former example relied only on guarantees made by the C programming language about structure layout and pointer convertibility, the latter example relies on assumptions about a particular system's hardware. Some situations, such as time-critical code that the compiler otherwise fails to optimize, may require
C# has explicit support for covariance and contravariance in generic types, [16]: 144 [20]: 23 unlike C++ which has some degree of support for contravariance simply through the semantics of return types on virtual methods. Enumeration members are placed in their own scope. The C# language does not allow for global variables or functions.
The process of verifying and enforcing the constraints of types—type checking—may occur at compile time (a static check) or at run-time (a dynamic check). If a language specification requires its typing rules strongly, more or less allowing only those automatic type conversions that do not lose information, one can refer to the process as strongly typed; if not, as weakly typed.
C# 4.0 is a version of the C# programming language that was released on April 11, 2010. Microsoft released the 4.0 runtime and development environment Visual Studio 2010 . [ 1 ] The major focus of C# 4.0 is interoperability with partially or fully dynamically typed languages and frameworks, such as the Dynamic Language Runtime and COM .