urgent...experts pls reply

[Unregistered]

question:
Add two very large long integers variables(say long integers with maximum permitted value) with the help of linked list.

when we add two long variables and save the result in a double variable ...the result is an unexpected one....though the double permits the value that we get in the result.
please explain it as soon as possible, why we cant save the result in a double and the possible solution of the above problem.

[Prelude]

You probably added the two longs together and then converted the result to a double. This will give you the incorrect value because the result of adding two longs is a long, thus you get overflow. According to C's type conversion rules, the return of an addition is the type of the longest floatiest operand. If you cast one of the operands to double then the result will be correct:

#include <stdio.h>
#include <limits.h>

int main ( void )
{
  long a, b;
  double result;
  a = b = LONG_MAX;
  /*
  ** This works.
  */
  result = (double)a + b;
  printf ( "%ld + %ld = %.0f\n", a, b, result );
  return 0;
}

#include <stdio.h>
#include <limits.h>

int main ( void )
{
  long a, b;
  double result;
  a = b = LONG_MAX;
  /*
  ** This does not.
  */
  result = (double)(a + b);
  printf ( "%ld + %ld = %.0f\n", a, b, result );
  return 0;
}

-Prelude

[The Dog]

>> longest floatiest operand

nice one. i think that should've been :
the variable with the highest comprehension.