Void null 0 有咩分別？

有咩分別? 根本三樣唔同野嚟
void: 行個method入面code, 但係唔return任何野
null: 吉, 冇野喺到
0: value = 0

假設你有個盒：

0：個盒入面有舊嘢係「0」
null：個盒入面冇嘢
void：直情無左個盒

喺大部分low level language嘅null == 0x0 == 0

一個係unit monad
一個係ternary logic
一個係real number
完

啊應該咁
https://en.wikipedia.org/wiki/Unit_type & https://en.wikipedia.org/wiki/Bottom_type
https://en.wikipedia.org/wiki/Three-valued_logic
https://en.wikipedia.org/wiki/Real_number

void: function return nothing
null: value is null
0: value is 0 / false

仲有void* 係同void完全冇關係

C/CPP

void = data type

0:
two scenario, integer 0 / pointer 0

int num = 0; // 單純 數數字既0  , 假設num既Memory address係 46
int* ptr_num = 0 // pointer variable 係0 姐係NULL
int * ptr_num = NULL // 同上面一樣
void* ptr_num = # // store  0個address落去 ptr_num  = 46

int num = 5;   // 假設係memory address 係46
 void* ptr_num = #
  
 std::cout << ptr_num;   // 46
 std::cout << *ptr_num; // Error Pointer points to a specific type of pointer

int 要對int
float 要對float
class 要對class

void type pointer = 單純store address
另外一點 Pointer本身佔Memory address
Pointer以外仲有reference

int num = 5;
 int& ref_num = num;
 int* ptr_num = #
  ref_num = 8;
  std::cout << num << std::endl;
  std::cout << ref_num << std::endl;
  std::cout << *ptr_num << std::endl;
std::cout << &num << std::endl;    // num's address
  std::cout << &ref_num << std::endl; // same as num's address

值得一題　reference variable 係唔佔memory address
而且中途係冇得改reference

hope it helps

利申:新手鳩嗡