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Why converting a base class pointer to a derived class pointer is consider dangerous by the compiler?
Wiki User
∙ 11y ago
There are two methods of casting one type to another: static casting and dynamic casting (both of which apply to pointers and references to objects). Statically casting a derived class to a base class is typesafe as the base class is guaranteed to exist if the derived class exists. However, static casting from a base class to a derived class is always considered dangerous as the conversion is not typesafe. Dynamic casting exists to cater for this scenario, however it is only possible when the base class is polymorphic (thus ensuring the required runtime information is available). If the conversion is not possible, the return value is NULL. However, it is considered bad programming practice to dynamically cast from a base class to a derived class. If the base class is polymorphic (which it must be), there is NEVER any need to dynamically cast between types. Virtual methods ensure correct behaviour. Whenever you are forced to dynamically cast from a base class to a derived class, consider redesigning the base class interface instead, as it is a clear sign of bad design. It is not dangerous, however; only static casting from a base class to a derived class is considered dangerous.
Wiki User
∙ 11y ago
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What are the importance of turbo c?
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What is late bound function call in C plus plus?
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How does virtual function support run time polymorphism?
Virtual functions are used to suport runtime polymorphism.In C++,if we have inheritance and we have overridden functions in the inherited classes,we can declare a base class pointer and make it to point to the objects of derived classes.When we give a keyword virtual to the base class functions,the compiler will no do static binding,so during runtime ,the base class pointer can be used to call the functions of the derived classes.Thus virtual functions support dynamic polymorphism.
Can a constructor be declared as virtual?
A constructor cannot be virtual because at the time when the constructor is invoked the virtual table would not be available in the memory. Hence we cannot have a virtual constructor. ## Constructor called implicitly not explicitly so constructor is not virtual.
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What are the importance of turbo c?
i came to know about that turbo c compiler is having 32 number of disadvantages........ i know about 10-12 disadvantages and i am sharing those wid u .... 1) Turbo c is a 16bit compiler ... means it can access about 16bits of data at a time... 2)Turbo c is based upon 8086 microprocessor... and it can run on x86family.... 3) Turbo c is derived from MS-DOS whereas GCC compiler which runs on linux..is a very good one as compared to Turbo C compiler..,.. 4)Also we cant do ODBC and Networking programming over the Turbo C comiler whereas we can do above programming in GCC compiler successfully by installing one ODBC library in it.... 5)we cant do graphics programming over here, rather we can do graphics programming. in GCC compiler using Glad Interface... 6) Turbo C compiler can access only 1mb of RAM, which is a demerit...whereas GCC compiler can access 4gb OF MEMORY.. 7) 7) Turbo C compiler is based upon MS DOS operating system.. which is a single process operating system..whereas GCC Compiler is based on 80386 processor(LINUX) and it is multiprocess operating system.....
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