CODEWITHSUNDEEP
cmacrossizeofc99
Lazureus
Lazureus

Reputation: 461

Universal macro for getting number elements in array or return just 1 when is used on variable?

In C language macro for getting number of array elements is well known and looks like this: 

uint32_t buffer[10];

#define ARRAY_SIZE(x)     sizeof(x)/sizeof(x[0])

size_t size = ARRAY_SIZE(buffer);

The question is, is there any universal macro for getting array elements or returning just one when it's used on variable ? I mean following usage of macro : 

uint32_t buffer[10];
uint32_t variable;

#define GET_ELEMENTS(x)     ???

size_t elements_of_array = GET_ELEMENTS(buffer); // returns 10
size_t elements_of_variable = GET_ELEMENTS(variable); // returns 1

Does anybody know the solution ?

I've edited my question because it was wrongly formulated, BTW I know that I can use : 

sizeof(variable)/sizeof(uint32_t)

Question is how to combine it in one macro or maybe inline function is better solution ?

Upvotes: 0

Views: 675

Answers (1)

gsamaras
gsamaras

Reputation: 73384

You could use sizeof, like this:

#include <stdio.h>

int main(void)
{
  unsigned int buffer[10];
  // size of one unsigned int
  printf("%zu\n", sizeof(unsigned int));

  // this will print the number of elements of buffer * size of an unsigned int
  printf("%zu\n", sizeof(buffer));

  // you have a mistake
  // the following printf() gives you the number of elements
  printf("%d\n", sizeof(buffer)/sizeof(buffer[0]));
  return 0;
}

Output (on my machine):

4
40
10

Regarding the edit you made:

You can't perform type checking in C, thus you can not check if what you pass is an array or a variable.

Upvotes: 3

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