typedef's have the advantage that they obey scope rules, that is they can be declared local to a function or a block whereas #define's always have a global effect.

Are the properties of i, j and x, y in the following program same?

typedef unsigned long int uli;
uli i, j;
unsigned long int x, y;

Is there any difference in the #define and typedef in the following code?

typedef char * string_t;
#define string_d char *;
string_t s1, s2;
string_d s3, s4;

Is the following declaration acceptable?

typedef long no, *ptrtono;
no n;
ptrtono p;

Point out the error in the following code?

typedef struct
{
    int data;
    NODEPTR link;
}*NODEPTR;