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copied!<p><strong>"(CREATESTRUCT*) lParam"</strong> form is called a c-style cast. When this is used the compiler would try all possible ways to convert the expression (lParam - here) to the type (CREATESTRUCT* - here).</p> <p>Let me explain all possible ways of casting,</p> <ol> <li>Casting from "const/volatile T" to T - in C++ a programmer picks this way using <strong>const_cast</strong></li> <li>Casting from "T" to "R" where T and R are related. E.g. like int/char, Car/Vehicle etc. - in C++ a programmer picks this way of casting using <strong>static_cast</strong>.</li> <li>Casting from "T" to "R" where T and R are related, along with runtime check. E.g. T = Vehicle and R = Car, conversion from T type object to R type object is valid statically but in reality (at runtime) compiler (through hidden code) has to check if the object being type-casted is indeed a Car or a derivative of Car. - in C++ a programmer picks this way of casting using <strong>dynamic_cast</strong>.</li> <li>Casting from "U" to "V" where U and V are unrelated. - in C++ a programmer picks this way of casting using <strong>reinterpret_cast</strong>.</li> </ol> <p>If a c-style cast is used in C++ by a programmer, he is telling the compiler to try all possible ways to convert/perceive an expression to/as a particular type.</p> <p>The only reason c-style cast is dangerous is because the real intention of the programmer is not properly conveyed to the compiler and fellow programmers who would be reading the code. Sometimes a programmer may only have meant a static_cast and not reinterpret_cast but using a c-style cast would cause an error at run-time which could have been caught at compile time. Because compiler error would occur if the programmer uses static_cast on unrelated types.</p> <p>And user defined cast operators affects some behaviors a bit more (esp. static_cast) but does not change the fundamentals.</p>

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