BigInteger

[cool dude]

i just learned BigInteger but i'm having a small problem.

code:

import java.math.BigInteger; public class Problem20 {         public static void main (String[] args){                 BigInteger n = BigInteger.valueOf(100);                 BigInteger total = BigInteger.valueOf(100);                                 for (int i = 1; i <= 99; i++){                         total = total.multiply(BigInteger.valueOf(n.subtract(BigInteger.valueOf(i))));                         }                         System.out.println(total);              } }

it says that cannot resolve symbol method valueOf(java.math.BigInteger) on line 8

[wtd]

The error is telling you there's no valueOf method that takes a BigInteger as an argument.

[cool dude]

wtd wrote:

The error is telling you there's no valueOf method that takes a BigInteger as an argument.

wat does that mean?

[wtd]

Look at the BigInteger API docs. Tell me what kind of arguments valueOf can take.

[cool dude]

wtd wrote:

Look at the BigInteger API docs. Tell me what kind of arguments valueOf can take.

isn't it Integers. thats wat it looks like when i look on the internet. they plug in a number (integer) inside the brackets. am i right?

[wtd]

/me sighs

code:

static BigInteger valueOf(long val)

It takes a "long" value, not a BigInteger object.

[cool dude]

ya i just figured it out a sec ago. i fixed it up, but i still have a question. if u did need a bigInteger value there instead of the long is there any way to have it?

[cool dude]

oh and how do u convert from a BigInteger to String

[wtd]

Look at the methods that are available for BigInteger objects.

You really need to learn how to read the API docs. That skill will be the key to either sinking or swimming with Java.

[cool dude]

i figured it out, but now when i'm adding all the digits in the number up i'm getting an error and i have no idea why

code:

import java.math.BigInteger; public class Problem20 {         public static void main (String[] args){                 int n = 100;                 int sum = 0;                 BigInteger total = BigInteger.valueOf(100);                                 for (int i = 1; i <= 99; i++){                         total = total.multiply(BigInteger.valueOf(n - i));                         }                         String stotal = total.toString();                         int k = stotal.length();                         for(int j = 1; j <= k; j++){                                 sum = sum + Integer.parseInt(stotal.substring(j,1));                                    }                                 System.out.println(sum);         } }

[wtd]

Read the error message. Think about the problem.

[cool dude]

wtd wrote:

Read the error message. Think about the problem.

they don't really give me an error message. usually when there's a problem i'm given an error message and shown the line number with the error. this time though it compiles and doesn't show any error message, but when i try to run it it doesn't run.

[wtd]

So it outputs nothing, you're saying?

[cool dude]

wtd wrote:

So it outputs nothing, you're saying?

Not exactly. when i compile it, usually it tells me there is an error but it doesn't. when i run it it says something but i have no clue wat it means.

[wtd]

What does it say?

(one step at a time...)