获得ArrayIndexOutOfBoundsException异常某一输入值之后 [英] Getting ArrayIndexOutOfBoundsException after a Certain INPUT value

问题描述

对于给定的低于code后的46348我得到 ArrayIndexOutOfBoundsException异常 INT输入值。我给定的条件在的为的循环，保持数组的限制条件。但不知何故，我得到这个例外，我无法弄清楚。我的要求是找到如下号码的所有primenumbers。

for the Given below code after int Input Value of 46348 i am getting ArrayIndexOutOfBoundsException. I am given Condition in for loop that keeps the array limits. But somehow i am getting this exception and i unable to figure it out. And my requirement is find all primenumbers below given number.

 Scanner sc = new Scanner(System.in);
    int n= sc.nextInt();
    int[] arr= new int[n+1];
            for(int i=2;i<=n;i++)
            {
                if(arr[i]==0)
                {
                    for(j=i;j*i<=n;j++)
                        arr[j*i]=1; // Here i am getting Exception
                }
            }

输入：

46349

输出：

java.lang.ArrayIndexOutOfBoundsException：-2146737495

java.lang.ArrayIndexOutOfBoundsException: -2146737495

502802

感谢。

推荐答案

您已经遇到了一个算术溢出。

You have encountered an arithmetic overflow.

在Java中， INT 数据类型是一个32位有符号整数，这意味着它可以-2147483648和2147483647之间的值。

In Java, int data type is a 32-bit signed integer, which means it can have values between -2147483648 and 2147483647.

在这一行：

for(j=i;j*i<=n;j++)

如果 I 是46349则Ĵ变得46349，太。如果通过46349乘以46349，将得到2148229801，比2147483647更大，所以整数溢出并变为-2146737495。当然，它小于46349，所以在在检查 -loop通行证。但是，你不能索引在Java负值的数组，这就是为什么你得到 ArrayIndexOutOfBoundsException异常。

If i is 46349 then j becomes 46349, too. If you multiply 46349 by 46349, you get 2148229801, which is greater than 2147483647, so the integer overflows and becomes -2146737495. Naturally, it is less than 46349, so the check in the for-loop passes. But you cannot index an array with a negative value in Java, that's why you get the ArrayIndexOutOfBoundsException.

范围检查你的输入值 N'LT; 46340 ，或者如果它真的需要与 N = 46349 输入，工作切换到长数据类型，这将工作到 N = 3037000499 。

Range check your input value for n < 46340, or if it really needs to work with n = 46349 input, switch to long data type, which will work up to n = 3037000499.

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