What declaration should be used to use variable as recursive?

Answer 1

Variables in C are not recursive. Functions are recursive.

Note that for functions to be truly recursive, they must only use arguments passed to them or automatic storage allocated from the stack. If they use other storage, they must implement a method of properly allocating and deallocating recursion instance variables. The classic example of a recursive function is the factorial function...

int factorial (int n) { if (n <= 2) return n; else return n * factorial (n-1); }

Data structures may have references to other elements of the same type, you might call this recursion - its also called self-referential structures. Example:

typedef struct TreeNode {

struct TreeNode *left, *right;
int data;

} TreeNode;