Variable-length Data Structure

Struct dirent {
.......
.......
Char A [1];}
Here char a [1]; the length is 1. It is generally considered that the character array can only store '/0', But here a [1] declares
Placed at the end of the struct, It is a variable-length data structure, which facilitates access to the address behind the struct, such:
[Copy to clipboard] [-] Code: struct dirent
{
Int Len;
Char A [0];
}; Struct dirent * Fun (char * STR, int Len)
{
Struct dirent * n = (struct dirent *) malloc (LEN + 1 + sizeof (struct dirent ));
If (! N)
Return NULL;
N-> Len = Len;
Memcpy (n-> A, STR, Len );
Return N;
} The size is extended when malloc is used, which is exactly at the end of struct (char a [0] or char a [1] must be the final member of the struct ),
In the memory, the extended address is adjacent to the last member char P [0], that is, access can be achieved through P,
The advantage of char P [0] Over char * P is:
(1) The former malloc does not need to be assigned to P, because the former is array.
(2) The former implements a dynamic array function. If it is not needed, it can occupy no memory at all, and the latter will occupy 4 bytes.