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However, any attempt to modify an object that is itself declared const by means of a const cast results in undefined behavior according to the ISO C++ Standard. In the example above, if ptr references a global, local, or member variable declared as const, or an object allocated on the heap via new int const, the code is only correct if ...
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.
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]
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 the below example, the method objectToString takes an Object parameter which is assumed to be of type String. public static String objectToString ( Object myObject ) { // This will only work when the myObject currently holding value is string. return ( String ) myObject ; } public static void main ( String [] args ) { // This will work since ...
Besides this feature, it is in C++ also possible to declare a function or method as const. This prevents such functions or methods from modifying anything but local variables. In C#, the keyword const exists, but does not have the same effect for function parameters, as it is the case in C/C++. There is, however, a way to "stir" the compiler to ...
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.
The dynamic_cast operator in C++ is used for downcasting a reference or pointer to a more specific type in the class hierarchy. Unlike the static_cast, the target of the dynamic_cast must be a pointer or reference to class. Unlike static_cast and C-style typecast