java 编写一个打印 1 2 ... userNum 的 For 循环？
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Writing a For loop that prints 1 2 ... userNum?
提问by Luke Harding
I am not sure what I am doing wrong here. Here is the original prompt:
我不确定我在这里做错了什么。这是原始提示：
"Write a for-loopthat prints: 1 2 .. userNum. Print a space after each number, including after the last number. Ex: userNum = 4prints:
1 2 3 4"
“写一个for-loop打印：1 2 .. userNum。在每个数字之后打印一个空格，包括最后一个数字之后。例如：userNum = 4打印：
1 2 3 4”
Here is my code:
这是我的代码：
import java.util.Scanner;
public class CountToNum {
public static void main (String [] args) {
int userNum = 0;
int i = 0;
userNum = 4;
for (userNum = 1; userNum <= 4; ++userNum) {
System.out.print(userNum + " ");
}
System.out.println("");
return;
}
}
回答by mech
Your for-loopneeds to use two different variables, one for checking against, and one for incrementing. You're also incrementing your variable before running the loop (++userNum), which means that you're counting from 2 to 4 instead of 1 to 4 like you meant to.
您for-loop需要使用两种不同的变量，一种用于检查，另一种用于递增。您还在运行循环 ( ++userNum)之前增加了变量，这意味着您从 2 到 4 计数，而不是像您打算的那样从 1 到 4。
So, in your case, you would do the following:
因此，在您的情况下，您将执行以下操作：
for (i = 1; i <= userNum; i++) {
System.out.print(i + " ");
}
回答by Flikk
for (i = 1; i <= userNum; i++) {
System.out.print(i + " ");
}
What else did you declare ifor?
You should use it when you declare it ;)
你还申报i了什么？您应该在声明时使用它；)
回答by ifly6
To print a range of numbers using a for-loop from 1 to a provided ending point, use this:
要使用从 1 到提供的结束点的 for 循环打印一系列数字，请使用以下命令：
for (int x = 0; x <= end; x++) {
System.out.println(x + " ");
}
I believe that the problem with the code that you presented is that you're mixing up the ending point (where you call it userNum) and the temporary variable with which you iterate (which I call x, though different conventions may use i).
我相信您提供的代码的问题在于您混淆了终点（您称之为userNum）和迭代的临时变量（我称之为x，尽管可能使用不同的约定i）。
