storing more than 2 power 31 on a 32-bit system

Question

I have to write a program that can calculate the powers of 2 power 2010 and to find the sum of the digits. eg:

if `2 power 12 => gives 4096 . So 4+0+9+6 = 19 . 

Now i need to find the same for 2 power 2010.

Please help me to understand.

Answer 1

Here's something to get you started:

char buf[2010]; // 2^2010 < 10^2010 by a huge margin, so buffer size is safe
snprintf(buf, sizeof buf, "%.0Lf", 0x1p2010L);

Answer 2

You have to either use a library that supplies unlimited integer length types (see http://en.wikipedia.org/wiki/Bignum ), or implement a solution that does not need them (e.g. use a digit array and implement the power calculation on the array yourself, which in your case can be as simple as addition in a loop). Since this is homework, probably the latter.