Declaring functions

From Cppreference

void: A function type that returns nothing

[edit] Example 1

void function() {
   std::cout << "Hello, World!" << std::endl;
   //no return
}

Output:

Hello, World!

void*: A pointer to the type void

[edit] Example 2

#include <iostream>
 
void print(void* p, char c) {
   if ( c == 'i' ) {
      std::cout << "*p = " << *static_cast<int*>(p) << std::endl;
   } else if ( c == 'c' ) {
      std::cout << "*p = " << *static_cast<char*>(p) << std::endl;
   } else if ( c == 's' ) {
      std::cout << "*p = " << static_cast<char*>(p) << std::endl;
   }
}
 
int main() {
   int i = 3;
   char c = '4';
   char s[] = "5";
 
   void* pi = &i;
   void* pc = &c;
   void* ps = &s;
   void* pf = reinterpret_cast<void*>(&print);
 
   reinterpret_cast<void(*)(void*, char)>(pf)(pi, 'i');
   reinterpret_cast<void(*)(void*, char)>(pf)(pc, 'c');
   reinterpret_cast<void(*)(void*, char)>(pf)(ps, 's');
}

Output:

*p = 3
*p = 4
*p = 5