void*指针的一些冷知识

Pointer (computer programming)
Pointer arithmetic cannot be performed on void pointers because the void type has no size, and thus the pointed address can not be added to, although gcc and other compilers will perform byte arithmetic on void* as a non-standard extension, treating it as if it were char *.

Pointer Arith
In GNU C, addition and subtraction operations are supported on pointers to void and on pointers to functions. This is done by treating the size of a void or of a function as 1.

so...sizeof(void *) = sizeof(char *) = 4.

by the way, sizeof(char) = 1.

如果一个变量point的类型是void*,他在point++ ，point = point + 1 等操作的时候，是往下数1个字节。因为void*会被默认当作char*