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The first two of these, const and volatile, are also present in C++, and are the only type qualifiers in C++. Thus in C++ the term " cv -qualified type" (for c onst and v olatile) is often used for "qualified type", while the terms " c -qualified type" and " v -qualified type" are used when only one of the qualifiers is relevant.
In addition, a (non-static) member-function can be declared as const. In this case, the this pointer inside such a function is of type object_type const * rather than merely of type object_type *. [2] This means that non-const functions for this object cannot be called from inside such a function, nor can member variables be modified.
C++ changes some C standard library functions to add additional overloaded functions with const type qualifiers, e.g. strchr returns char* in C, while C++ acts as if there were two overloaded functions const char *strchr(const char *) and a char *strchr(char *). In C23 generic selection is used to make C's behaviour more similar to C++'s. [11]
Even functions can be const in C++. The meaning here is that only a const function may be called for an object instantiated as const; a const function doesn't change any non-mutable data. C# has both a const and a readonly qualifier; its const is only for compile-time constants, while readonly can be used in constructors and other runtime ...
Existing Eiffel software uses the string classes (such as STRING_8) from the Eiffel libraries, but Eiffel software written for .NET must use the .NET string class (System.String) in many cases, for example when calling .NET methods which expect items of the .NET type to be passed as arguments. So, the conversion of these types back and forth ...
In C and C++, constructs such as pointer type conversion and union — C++ adds reference type conversion and reinterpret_cast to this list — are provided in order to permit many kinds of type punning, although some kinds are not actually supported by the standard language.
Notice that the type of the result can be regarded as everything past the first supplied argument. This is a consequence of currying, which is made possible by Haskell's support for first-class functions; this function requires two inputs where one argument is supplied and the function is "curried" to produce a function for the argument not supplied.
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.