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The void pointer, or void*, is supported in ANSI C and C++ as a generic pointer type. A pointer to void can store the address of any object (not function), [a] and, in C, is implicitly converted to any other object pointer type on assignment, but it must be explicitly cast if dereferenced.
A program can convert a pointer to any type of data (except a function pointer) to a pointer to void and back to the original type without losing information, which makes these pointers useful for polymorphic functions. The C language standard does not guarantee that the different pointer types have the same size or alignment.
In conditional contexts, null pointer values evaluate to false, while all other pointer values evaluate to true. Void pointers (void *) point to objects of unspecified type, and can therefore be used as "generic" data pointers. Since the size and type of the pointed-to object is not known, void pointers cannot be dereferenced, nor is pointer ...
The function returns an untyped pointer (type void *), which the calling code must explicitly or implicitly cast to the appropriate pointer type. Pre-standardized implementations of C required an explicit cast to do so, therefore the code (struct foo *) malloc( sizeof (struct foo)) became the accepted practice.
Check the return value of all non-void functions, or cast to void to indicate the return value is useless. Use the preprocessor sparingly. Limit pointer use to a single dereference, and do not use function pointers. Compile with all possible warnings active; all warnings should then be addressed before release of the software.
malloc returns a void pointer (void *), which indicates that it is a pointer to a region of unknown data type. The use of casting is required in C++ due to the strong type system, whereas this is not the case in C. One may "cast" (see type conversion) this pointer to a specific type:
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Void safety (also known as null safety) is a guarantee within an object-oriented programming language that no object references will have null or void values. In object-oriented languages, access to objects is achieved through references (or, equivalently, pointers ).