I've seen several macros for array length floating around:

From this question:

  • #define length(array) (sizeof(array)/sizeof(*(array)))
  • #define ARRAY_LENGTH(array) (sizeof((array))/sizeof((array)[0]))
  • #define SIZE(array, type) (sizeof(array) / (sizeof(type))

And Visual Studio's _countof:

#define _countof(_Array) (sizeof(_Array) / sizeof(_Array[0]))

What I'd like to know is:

  1. What's the difference between those using array[0] and *array?
  2. Why should either be preferred?
  3. Do they differ in C++?
c++ c arrays c-preprocessor
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