重排代码片段后出现额外的 '-'。

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英文:

Getting a extra '-' after rearranging the code snippets

问题

  1. 我从《Head First Java》这本书开始学习 Java，偶然间遇到了一个练习。我需要重新排列这些代码片段，以获得以下输出：

a-b c-d

  1. 代码片段如下：

if (x == 1) {
System.out.print("d");
x = x - 1;
}

if (x == 2) {
System.out.print("b c");
}

if (x > 2) {
System.out.print("a");
}

while (x > 0) {

x = x - 1;
System.out.print("-");

int x = 3;

  1. 所以我做了类似这样的操作：

public class cc {
public static void main(String [] args) {
int x = 3;
while (x > 0) {
if (x == 2) {
System.out.print("b c");
}
if (x > 2) {
System.out.print("a");
}
if (x == 1) {
System.out.print("d");
}
x = x - 1;
System.out.print("-");
}
}
}

  1. 我得到的输出是：

a-b c-d-

  1. 我做错了什么？
英文:

So I started learning java from the Head First Java book and stumbled upon a exercise.I need to rearrange these code snippets to obtain a output like this:

  1. a-b c-d

The code snippets are:

  1. if (x == 1) {
  2. 				System.out.print("d");
  3.                 x = x - 1
  4. 			}
  1. if (x == 2) {
  2. 				System.out.print("b c");
  3. 			}
  1. if (x > 2) {
  2. 				System.out.print("a");
  3.            }
  1. while (x > 0) {
  1. x = x - 1;
  2. System.out.print("-");
  1. int x = 3;

So I did something like this:

  1. public class cc {
  2. 	public static void main(String [] args) {
  3. 		int x = 3;
  4. 		while (x > 0) {
  5. 			if (x == 2) {
  6. 				System.out.print("b c");
  7. 			}
  8. 			if (x > 2) {
  9. 				System.out.print("a");
  10. 			}
  11. 			if (x == 1) {
  12. 				System.out.print("d");
  13. 			}
  14. 			x = x - 1;
  15. 			System.out.print("-");
  16. 		}
  17. 		
  18. 	}
  20. }

The output I am getting is :

  1. a-b c-d-

What did I do wrong

答案1

得分: 4

你在一个if语句中漏掉了一个x = x - 1;，并且把打印语句放错了位置：

  1. public class cc {
  2.     public static void main(String [] args) {
  3.         int x = 3;
  4.         while (x > 0) {
  5.             if (x == 2) {
  6.                 System.out.print("b c");
  7.             }
  8.             if (x > 2) {
  9.                 System.out.print("a");
  10.             }
  11.             x = x - 1;
  12.             System.out.print("-");
  13.             if (x == 1) {
  14.                 System.out.print("d");
  15.                 x = x - 1;
  16.             }
  17.         }
  19.     }
  20. }
英文:

You missed one x = x - 1; in one of the if statements, and put the print statement in the wrong place:

  1. public class cc {
  2.     public static void main(String [] args) {
  3.         int x = 3;
  4.         while (x > 0) {
  5.             if (x == 2) {
  6.                 System.out.print("b c");
  7.             }
  8.             if (x > 2) {
  9.                 System.out.print("a");
  10.             }
  11.             x = x - 1;
  12.             System.out.print("-");
  13.             if (x == 1) {
  14.                 System.out.print("d");
  15.                 x = x - 1;
  16.             }
  17.         }
  19.     }
  20. }

答案2

得分: 1

  1. public class cc {
  2.     public static void main(String [] args) {
  3.         int x = 3;
  4.         while (x > 0) {
  5.             if (x > 2) {
  6.                 System.out.print("a");
  7.             }
  8.             if (x == 2) {
  9.                 System.out.print("b c");
  10.             }
  11.             x = x - 1;
  12.             System.out.print("-");
  13.             if (x == 1) {
  14.                 System.out.print("d");
  15.                 x = x - 1;
  16.             }
  17.         }
  19.     }
  20. }
英文: 
  1. public class cc {
  2.     public static void main(String [] args) {
  3.         int x = 3;
  4.         while (x > 0) {
  5.             if (x == 2) {
  6.                 System.out.print("b c");
  7.             }
  8.             if (x > 2) {
  9.                 System.out.print("a");
  10.             }
  11.             if (x == 1) {
  12.                 System.out.print("d");
  13.             }
  14.             x = x - 1;
  15.             System.out.print("-"); // will run for every iteration of the loop
  16.         }
  17.         
  18.     }
  20. }

Looking at your code here, after each iteration of the loop regardless of the value of x, it will always print a dash after the output. You are also missing x = x - 1; from

  1. if (x == 1) {
  2.                 System.out.print("d");
  3.                 x = x - 1; // you were missing this
  4.             }

The if statement above should also go below

  1. x = x - 1;
  2. System.out.print("-");

so that we don't add an unnecessary - at the end by setting x == 1 before the condition is checked so we don't go through another iteration.

Putting this all together we get this

  1. public class cc {
  2.     public static void main(String [] args) {
  3.         int x = 3;
  4.         while (x > 0) {
  5.             if (x > 2) {
  6.                 System.out.print("a");
  7.             }
  8.             if (x == 2) {
  9.                 System.out.print("b c");
  10.             }
  11.             x = x - 1;
  12.             System.out.print("-");
  13.             if (x == 1) {
  14.                 System.out.print("d");
  15.                 x = x - 1;
  16.             }
  17.         }
  19.     }
  20. }

EDIT: I also rearranged the if statements for you as > 2 coming before == 2 makes more logical sense

答案3

得分: -1

以下是翻译好的部分：

练习的重点是理解循环（在这种情况下是while循环）、if语句以及修改存储在变量中的值。为此，我建议您还可以查看数组，并尝试生成所需的输出。例如，这种特定情况将打印a-b c-d，但一般情况是什么呢？如果您有一堆字符，看起来它们应该被分成成对的元素，其中每对元素由空格分隔，任何给定对的每个元素之间都有一个连字符。

因此，假设您有

  1. String input = "abcd";

您需要编写什么代码才能获得输出

  1. a-b c-d

其中一种可能性是以下内容

  1. char[] chars = input.toCharArray();
  2. int i = 0;
  3. while (i < chars.length) {
  4.     String separator;
  5.     System.out.print(chars[i]);
  6.     if (i == chars.length - 1) {
  7.         separator = "\n";
  8.     else if (i % 2 != 0) {
  9.         separator = " ";
  10.     } else {
  11.         separator = "-";
  12.     }
  13.     System.out.print(separator);
  14.     i++;
  15. }
英文:

The point of the exercise is to understand loops (in this case a while loop), if statements and modifying the value stored in a variable. To that end I would suggest also looking at arrays and trying to generate the desired output. For example this specific case will print a-b c-d but what's the general case? If you have a bunch of characters it looks like they are to be broken into pairs where each pair is separated by a space and between each element of any given pair there is a hyphen.

So supposing you have

  1. String input = &quot;abcd&quot;;

What do you have to write to get

  1. a-b c-d

In output?

One possibility is the following

  1. char[] chars = input.toCharArray();
  2. int i = 0;
  3. while (i &lt; chars.length) {
  4.     String separator;
  5.     System.out.print(chars[i]);
  6.     if (i == chars.length - 1) {
  7.         separator = &quot;\n&quot;;
  8.     else if (i % 2 != 0) {
  9.         separator = &quot; &quot;;
  10.     } else {
  11.         separator = &quot;-&quot;;
  12.     }
  13.     System.out.print(separator);
  14.     i++;
  15. }

huangapple
  • 本文由 发表于 2020年8月22日 02:08:11
  • 转载请务必保留本文链接：https://go.coder-hub.com/63527994.html
  • java
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