printf  can be used as a variable . But once we declare a variable printf ,
standard Library function "printf"  can not be recongnized by the compiler within   the scope of the variable  (reason :local symbol might be having higher precedence ).
If at all library func is  used ,compiler  wil throw the error saying- " called object is not a function."

For eg : below  is an  error free C program :

#include <stdio.h>
int main()

{
     int printf;
     printf = 10;
  /*  printf("n My Number = %d",num);*/  /* Activating this line,causes an error */
     Display( printf);
    return 1;
}

Display(int num)
{
    printf("n My Number = %d",num);
}

Note : But in programming it is not recommended to  use the sandard symbols.



-Jayalakshmi  Kaja