C-Language flexible array (variable-length array) __c language

Variable arrays are already supported in C99, but not supported in VC, but flexible arrays (special variable-length arrays) are supported.

What is a flexible array, how to use it. Please look at the code below.

#include <stdio.h>
#include <string.h>
#include <malloc.h>
///Flexible array////
*
The last element in the C99 is allowed to be an array of unknown size, which is called a flexible array member, and the
flexible array member must precede at least one other member.
* *
typedef struct _FLEX_ARRAY
{
	int nlen;
	Char szbuff[];//flexible array member
} Flex_array,*pflex_array;

int main ()
{
	char szmsg[] = "This is a C programe.";

	Structure body size equals 4
	int stsize = sizeof (Pflex_array);//=sizeof (int)
	//allocating memory
	pflex_array Psta = (pflex_array) malloc (Stsize + 100*sizeof (char));
	
	Ordinary members and flexible array members in a structure are assigned
	Psta->nlen = strlen (szmsg);
	memcpy (psta->szbuff,szmsg,psta->nlen+1);
	
	Structure body size stsize still equals 4 Description: The flexible array is not actually a member of the structure body
	stsize = sizeof (PSTA);

	Freeing memory free
	(PSTA);

	return 0;
}