array out of bounds

[cool dude]

i made this sample program test however i'm getting an array out of bounds error and i can't seem to fix it.

code:

import java.math.*; public class Problem25 {         public static void main (String[] args) {                 BigInteger[] num = new BigInteger[2];                                                 for (int i = 0; i < 3; i++) {                         if (i == 0) {                                 num[0] = BigInteger.valueOf(1);                         }                         if (i == 1) {                                 num[1] = BigInteger.valueOf(1);                         }                         else {                                 num[i] = num[i-1].add(num[i-2]);                                        }                 }                 System.out.println(num[2]);         } }

[rizzix]

code:

BigInteger[] num = new BigInteger[3];

3 not 2. It's the length not the last index.

[[Gandalf]]

So to prevent things like this from happening in the future, use num.length instead of a constant number which really has nothing to do with your array. The loop would become:

code:

for (int i = 0; i < num.length; i++) ...

Though this brings up the question of... Do you not understand arrays yet, or did you simply overlook this? Arrays are much more important to understand than BigIntegers.

[cool dude]

thanks. one more question. how would you get the length of the number of digits in the array. for example if the number was 1234 it would tell me that its 4 digits long. i tried using lenght(); but it doesn't work. it says, "cannot resolve symbol method length()"

[cool dude]

here's my code:

code:

import java.math.*; public class Problem25 {         public static void main (String[] args) {                 BigInteger[] num = new BigInteger[7];                                 num[0] = BigInteger.ONE;                 num[1] = BigInteger.ONE;                 for (int i = 2; i < num.length; i++) {                         num[i] = num[i-1].add(num[i-2]);                         if (length(num[i]) >= 2) {                                 System.out.println(num[i]);                                   }                 }         } }

[wtd]

Where does the method "length" come from?

[cool dude]

wtd wrote:

Where does the method "length" come from?

what do you mean where it comes from? i've always been able to do something like :

code:

num.length();

but because this is an array i can't do it the same way i'm guessing.

[wtd]

Back to Java 101.

All methods live inside classes. Which class does the length method live in?

[cool dude]

wtd wrote:

Back to Java 101.

All methods live inside classes. Which class does the length method live in?

oh i see. the string class. so now i have to convert the array to a string. but how?

[cool dude]

just figured it out. thanks for the help