title: What does void* mean and how to use it?
body: <p>Today when I was reading others' code, I saw something like <code>void *func(void* i);</code>, what does this <code>void*</code> mean here for the function name and for the variable type, respectively? </p>
  
  <p>In addition, when do we need to use this kind of pointer and how to use it? </p>