biginteger

This is quite an odd problem I know, but I'm trying to get a copy of the current largest prime number in a file. Getting the number in integer form is fairly easy. I just run this. prime = 2**74207281 - 1 It takes about half a second and it works just fine. Operations are fairly quick as well. Dividing it by 10 (without decimals) to shift the digits is quick. However, str(prime) is taking a very long time. I reimplemented str like this, and found it was processing about a hundred or so digits per second. while prime > 0: strprime += str(prime%10) prime //= 10 Is there a way to do this more

I have a BigInteger value, let's say it is 282 and is inside the variable x. I now want to write a while loop that states: while b2 isn't a perfect square: a ← a + 1 b2 ← a*a - N endwhile How would I do such a thing using BigInteger? EDIT: The purpose for this is so I can write this method . As the article states one must check if b2 is not square. Compute the integer square root, then check that its square is your number. Here is my method of computing the square root using Heron's method : private static final BigInteger TWO = BigInteger.valueOf(2); /** * Computes the integer square root of

I converted a String to BigInteger as follows: Scanner sc=new Scanner(System.in); System.out.println("enter the message"); String msg=sc.next(); byte[] bytemsg=msg.getBytes(); BigInteger m=new BigInteger(bytemsg); Now I want my string back. I'm using m.toString() but that's giving me the desired result. Why? Where is the bug and what can I do about it? You want to use BigInteger.toByteArray() String msg = "Hello there!"; BigInteger bi = new BigInteger(msg.getBytes()); System.out.println(new String(bi.toByteArray())); // prints "Hello there!" The way I understand it is that you're doing the