What is a void pointer in C

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Possible Duplicate    What is a void pointer and what is a null pointer        I often see code which resembles something like the following   void   foo int bar    What does this mean  Does it mean that it can return anything  Is this similar to dynamic or object in C

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A void  pointer is used when you want to indicate a pointer to a hunk of memory without specifying the type  C s malloc returns such a pointer  expecting you to cast it to a particular type immediately  It really isn t useful until you cast it to another pointer type  You re expected to know which type to cast it to  the compiler has no reflection capability to know what the underlying type should be

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Void is used as a keyword   The void pointer  also known as the generic pointer  is a special type of pointer that can be pointed at objects of any data type  A void pointer is declared like a normal pointer  using the void keyword as the pointer   s type   General Syntax   void  pointer variable   void  pVoid     pVoid is a void pointer   A void pointer can point to objects of any data type   int nValue  float fValue   struct Something       int nValue      float fValue      Something sValue   void  pVoid  pVoid    amp nValue     valid pVoid    amp fValue     valid pVoid    amp sValue     valid   However  because the void pointer does not know what type of object it is pointing to  it can not be dereferenced  Rather  the void pointer must first be explicitly cast to another pointer type before it is dereferenced   int nValue   5  void  pVoid    amp nValue      can not dereference pVoid because it is a void pointer  int  pInt   static cast lt int  gt  pVoid      cast from void  to int   cout  lt  lt   pInt  lt  lt  endl     can dereference pInt   Source  link

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A void  does not mean anything  It is a pointer  but the type that it points to is not known   It s not that it can return  anything   A function that returns a void  generally is doing one of the following    It is dealing in unformatted memory  This is what operator new and malloc return  a pointer to a block of memory of a certain size  Since the memory does not have a type  because it does not have a properly constructed object in it yet   it is typeless  IE  void  It is an opaque handle  it references a created object without naming a specific type  Code that does this is generally poorly formed  since this is better done by forward declaring a struct class and simply not providing a public definition for it  Because then  at least it has a real type  It returns a pointer to storage that contains an object of a known type  However  that API is used to deal with objects of a wide variety of types  so the exact type that a particular call returns cannot be known at compile time  Therefore  there will be some documentation explaining when it stores which kinds of objects  and therefore which type you can safely cast it to    This construct is nothing like dynamic or object in C   Those tools actually know what the original type is  void  does not  This makes it far more dangerous than any of those  because it is very easy to get it wrong  and there s no way to ask if a particular usage is the right one   And on a personal note  if you see code that uses void  s  often   you should rethink what code you re looking at  void  usage  especially in C    should be rare  used primary for dealing in raw memory

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A void  can point to anything  it s a raw pointer without any type info

[c++] What is a void pointer in C++?

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