# Thread: help with fibonacci problem

1. Member
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Dec 2008
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## help with fibonacci problem

ok so i want to find the position in the fibonacci series of the first number with 1000 digits.. heres what i have so far
Java Code:
public class pe25 {
public static void main(String [] args) {
//initialize variables
Integer a = new Integer(0);
Integer b = new Integer(1);
String s = ""; // would just put String s; but i need to use the length
// of it in the while loop
int count = 0; // what number in the series the number is
while (s.length() < 1000){
count++;
b = a + b;
a = b - a;
s = a.toString();
System.out.println(s);// just for testing
}
System.out.println(count);
}

}
however heres the first numbers in the output..
Java Code:
1
1
2
3
5
8
13
21
34
55
89
144
233
377
610
987
1597
2584
4181
6765
10946
17711
28657
46368
75025
121393
196418
317811
514229
832040
1346269
2178309
3524578
5702887
9227465
14930352
24157817
39088169
63245986
102334155
165580141
267914296
433494437
701408733
1134903170
1836311903
-1323752223
512559680
-811192543
-298632863
-1109825406
-1408458269
1776683621
368225352
2144908973
-1781832971
notice how they are right for a while then suddenly jump to being negative..
i have no idea why this isnt working as i programming basically the exact same thing in python and it works perfectly.. heres the python code if anyone cares..
Java Code:
a = 0
b = 1
count = 0
while len(str(a)) < 1000:
count += 1
b = a+b
a = b-a
print count

2. Your number is becoming too large for an Integer to hold. Try using long or BigInteger.

Your code breaks at right under 3 billion or about 2^32. I'm not sure the highest that Integer can hold(perhaps someone can toss that in?)

3. Member
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ahh i see thanks.. heres what i ended up with
Java Code:
import java.math.BigInteger;

public class pe25 {
public static void main(String [] args) {
//initialize variables
BigInteger a = new BigInteger("0");
BigInteger b = new BigInteger("1");
String s = ""; // would just put String s; but i need to use the length
// of it in the while loop
int count = 0; // what number in the series the number is
while (s.length() < 1000){
count++;
a = b.subtract(a);
s = a.toString();
}
System.out.println(count);
}

}

4. Senior Member
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Nov 2007
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To see the highest value of an Integer:
System.out.println(Integer.MAX_VALUE);

5. I'm assuming BigInteger worked then?

And thanks carderne I always forget I can view public variables within java classes(even though I always use MyClass.myVariable lol)

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