Problem with recursive funtion

Hi!

I have a problem with this recursive function. Tell me what changes variables i and j.

Code:

# include <stdio.h>
# include <string.h>
# include <stdlib.h>
# include <ctype.h>

# define MAX 1001

typedef struct st
{
	int dat;
	struct st *left;
	struct st *right;
};
typedef struct st* OBST;

BST B_Tree(int i, int j)
{
	OBST New = (OBST)malloc(sizeof(struct st));
	int x;

	if(i == j)
	{
		New = NULL;
		return New;
	}
	else
	{
		x = r[i][j];
		New->dat = keys[x];			//write key
		New->right = B_Tree(x, j);	//repeat
		New->left = B_Tree(i, x-1);	
		printf ("\ni = %d\tj = %d\tx = %d", i, j, x);
		return New;
	}
}
int main ()
{
    OBST root;

    root = B_Tree(0, 1000);
    return 0;
}

New->right = B_Tree(x, j);
New->left = B_Tree(i, x-1);
You are calling the function here with different values.

Yes I know that but how are i and j variables changed. In B_Tree function there is nothing like i++ or j++ (i-- or j--) that would change the values. So please explain this to me.

Not sure what you mean but here

New->right = B_Tree(x, j);

you call B_Tree with a different value for i. The value for i in the new call is equal to x. And here

New->left = B_Tree(i, x-1);

The value for j in the new call is equal to x-1.