我的数组在翻转和反转时为什么显示为0?

huangapple go评论47阅读模式
英文:

Why is my array showing 0s when I flip it and reverse it?

问题

尝试反转用户输入的数组。

我的代码

Scanner s = new Scanner(System.in);
System.out.println("输入数字:");
int[] array = new int[5];
int[] reversed = new int[array.length];
for (int i = 0; i < array.length; i++) {
    array[i] = s.nextInt();
    reversed[i] = array[array.length - 1 - i];
}
System.out.println(Arrays.toString(reversed));

当我输入:

10
20
30
40
50

我得到:

输出:
[0, 0, 30, 20, 10]

然而,当我硬编码数字时,它正常工作。

int[] array = {10, 20, 30, 40, 50};
int[] reversed = new int[array.length];
for (int i = 0; i < array.length; i++) {
    reversed[i] = array[array.length - 1 - i];
}
System.out.println(Arrays.toString(reversed));

我得到:

[50, 40, 30, 20, 10]

不确定我在这里做错了什么。我知道有其他方法可以做同样的事情,但我正在尝试弄清楚为什么我这样做会出现问题。

英文:

Trying to reverse an user-input array.

My code

    Scanner s = new Scanner(System.in);
    System.out.println(&quot;Enter numbers: &quot;);
    int[] array = new int[5];
    int[] reversed = new int[array.length];
    for (int i = 0; i &lt; array.length; i++) {
        array[i] = s.nextInt();
        reversed[i] = array[array.length - 1 - i];
    }
    System.out.println(Arrays.toString(reversed));

When I enter:

 10
 20
 30
 40
 50

I get:

 output:
 [0, 0, 30, 20, 10]

Yet when I hardcode numbers, it works just fine.

  int[] array = {10, 20, 30, 40, 50};
    int[] reversed = new int[array.length];
    for (int i = 0; i &lt; array.length; i++) {
        reversed[i] = array[array.length - 1 - i];
    }
    System.out.println(Arrays.toString(reversed));

I get back:

 [50, 40, 30, 20, 10]

Not sure what I'm doing wrong here. I know there are other ways to do the same thing but I'm trying to figure out why the way I'm doing it is giving me issues.

答案1

得分: 2

你正在从开头到结尾填充数组,并且在填充 reversed 之前,你正在使用尚未填充的 array 中的值!

具体来说,一旦你尝试填充 reversed[0],你使用的是尚未填充的 array[4]

你可以通过先填充 array,然后在第一个循环完成后再开始用第二个循环填充 reversed 来克服这个问题。

英文:

You are filling your arrays from beginning to end, and you are filling reversed with values from array, before they were populated!

Specifically, once you try to fill reversed[0], you use array[4], which was not populated yet.

You can overcome it, by first filling array, and start filling reversed in a second loop after the first is complete.

答案2

得分: 2

将这一行代码更改为:

reversed[array.length-1-i] = array[i];

如注明的那样,您正在尝试在数组填充之前访问它。

英文:

just change this line:

 reversed[i] = array[array.length - 1 - i];

to:

 reversed[array.length-1-i] = array[i];

as noted you are trying to access array before it is filled

答案3

得分: 0

尝试使用以下代码来实现数组的反转:

import java.util.Scanner;
import java.util.Arrays;

public class Main {

    public static void main(String args[]) {

        Scanner s = new Scanner(System.in);
        System.out.println("Enter numbers: ");
        int[] array = new int[5];
        int[] reversed = new int[array.length];
        for (int i = 0; i < array.length; i++) {
            array[i] = s.nextInt();
        }

        int j = array.length;
        for (int i = 0; i < array.length; i++) {
            reversed[j - 1] = array[i];
            j = j - 1;
        }

        System.out.println("Reversed array is: \n");
        for (int k = 0; k < array.length; k++) {
            System.out.println(reversed[k]);
        }
    }
}

输出:

Enter numbers:
1
2
3
4
5
Reversed array is:

5
4
3
2
1
英文:

Try the below code to implement the reversal of the array :

import java.util.Scanner;
import java.util.Arrays;


public class Main {
    
	public static void main(String args[]) { 
        
        Scanner s = new Scanner(System.in);
        System.out.println(&quot;Enter numbers: &quot;);
        int[] array = new int[5];
        int[] reversed = new int[array.length];
        for (int i = 0; i &lt; array.length; i++) {
            array[i] = s.nextInt();
        }

        int j = array.length; 
        for (int i = 0; i &lt; array.length; i++) { 
            reversed[j - 1] = array[i]; 
            j = j - 1; 
        } 

        System.out.println(&quot;Reversed array is: \n&quot;); 
        for (int k = 0; k &lt; array.length; k++) { 
            System.out.println(reversed[k]); 
        } 
    } 
}

Output :

Enter numbers:                                                                                                                                                
1                                                                                                                                                             
2                                                                                                                                                             
3                                                                                                                                                             
4                                                                                                                                                             
5                                                                                                                                                             
Reversed array is:

5                                                                                                                                                             
4                                                                                                                                                             
3                                                                                                                                                             
2                                                                                                                                                             
1 

huangapple
  • 本文由 发表于 2020年7月28日 01:16:51
  • 转载请务必保留本文链接:https://go.coder-hub.com/63120313.html
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