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I've searched but couldn't find any results (my terminology may be off) so forgive me if this has been asked before.
I was wondering if there is an easy way to call a void* as a function in C without first declaring a function pointer and then assigning the function pointer the address;
ie. assuming the function to be called is type void(void)
void *ptr;
ptr = <some address>;
((void*())ptr)(); /* call ptr as function here */
with the above code, I get error C2066: cast to function type is illegal in VC2008
If this is possible, how would the syntax differ for functions with return types and multiple parameters?
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Void functions are created and used just like value-returning functions except they do not return a value after the function executes. In lieu of a data type, void functions use the keyword "void." A void function performs a task, and then control returns back to the caller--but, it does not return a value.
Void functions, also called nonvalue-returning functions, are used just like value-returning functions except void return types do not return a value when the function is executed. The void function accomplishes its task and then returns control to the caller. The void function call is a stand-alone statement.
Function Pointer Syntaxvoid (*foo)( int ); In this example, foo is a pointer to a function taking one argument, an integer, and that returns void. It's as if you're declaring a function called "*foo", which takes an int and returns void; now, if *foo is a function, then foo must be a pointer to a function.
A void pointer in C++ is a special pointer that can point to objects of any data type. In other words, a void pointer is a general purpose pointer that can store the address of any data type, and it can be typecasted to any type. A void pointer is not associated with any particular data type.
Your cast should be:
((void (*)(void)) ptr)();
In general, this can be made simpler by creating a typedef for the function pointer type:
typedef void (*func_type)(void);
((func_type) ptr)();
I should, however, point out that casting an ordinary pointer (pointer to object) to or from a function pointer is not strictly legal in standard C (although it is a common extension).
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