嵌套循环：用 Java 打印座位
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原文地址: http://stackoverflow.com/questions/28758232/
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Nested loops: Print seats in java
提问by Gui
Given numRows and numCols, print a list of all seats in a theater. Rows are numbered, columns lettered, as in 1A or 3E. Print a space after each seat, including after the last. Use separate print statements to print the row and column. Ex: numRows = 2 and numCols = 3 prints: 1A 1B 1C 2A 2B 2C
给定 numRows 和 numCols，打印剧院中所有座位的列表。行有编号，列有字母，如 1A 或 3E。在每个座位之后打印一个空格，包括最后一个之后。使用单独的打印语句打印行和列。例如：numRows = 2 和 numCols = 3 打印：1A 1B 1C 2A 2B 2C
My code's like:
我的代码是这样的：
public static void main(String[] args) {
int numRows = 2;
int numCols = 3;
int rows = 0;
int cols = 1;
char col;
while (rows < numRows) {
rows++;
col='A';
while (cols <= numCols) {
System.out.print("" + rows + col + " ");
col++;
cols++;
}
}
System.out.println(" ");
return;
}
}
And my output's like:
我的输出是这样的：
1A 1B 1C
I tried to make it like:
我试着让它像：
1A 1B 1C 2A 2B 2C
Why my loop stop at 1?
为什么我的循环在 1 处停止？
采纳答案by Parasu
add a line cols = 1;just after rows++;
cols = 1;在后面添加一行rows++;
回答by Chris Jester-Young
You didn't reset the value of colsin the outer loop. So the second time through the outer loop, the inner loop never gets run at all. Also consider using a forloop:
您没有重置cols外循环中的值。所以第二次通过外循环时，内循环根本不会运行。还可以考虑使用for循环：
for (int rows = 0; rows < numRows; ++rows) {
// ...
for (int cols = 0; cols < numCols; ++cols) {
// ...
}
}
回答by TSKSwamy
Just change the position of cols = 1;
只需改变位置 cols = 1;
public static void main(final String[] args){
int numRows = 2;
int numCols = 3;
int rows = 0;
while (rows < numRows) {
rows++;
int cols = 1;
char col = 'A';
while (cols <= numCols) {
System.out.print("" + rows + col + " ");
col++;
cols++;
}
}
System.out.println(" ");
}
回答by lomsansnom
On the first iteration, when it goes over the inner while, you update the value of "cols". So when this while is done, cols = 3.
在第一次迭代中，当它越过内部 while 时，更新“cols”的值。所以当这个while完成时，cols = 3。
Then on the second iteration, you still have cols=3 which is > numCols so it doesn't execute the while loop.
然后在第二次迭代中，您仍然有 cols=3，即 > numCols，因此它不会执行 while 循环。
As said Parasu just add "cols = 1;" before the inner loop and it'll works.
正如 Parasu 所说，只需添加“cols = 1;” 在内循环之前，它会起作用。
回答by jam
This uses a for loop
这使用了一个 for 循环
public class NestedLoops {
public static void main (String [] args) {
int numRows = 2;
int numCols = 3;
int i = 0;
int j = 0;
char rows;
char columns;
rows = '1';
for (i = 0; i < numRows; ++i) {
columns = 'A';
for (j = 0; j < numCols; ++j) {
System.out.print("" + rows + columns + " ");
columns++;
}
rows++;
}
System.out.println("");
return;
}
}
回答by Cosmopus
public class NestedLoops_2 {
public static void main (String [] args) {
int numRows = 2;
int numCols = 5;
for (int i = 1; i <= numRows; i++){
char abc = 'A';
for (int j = 1; j <= numCols; ++j) {
System.out.print("" + i + abc + " ");
++abc;
}
}
System.out.println("");
return;
}
}
回答by user8971882
You have to just make a small change in your code. After the inner while loop but just inside the outer while loop write cols=1;... because the next time when the loop reaches the same inner while loop cols have to again start at 1 and not at some other value .
您只需对代码进行一些小的更改。在内部 while 循环之后但在外部 while 循环内部写入 cols=1;... 因为下一次当循环到达相同的内部 while 循环时 cols 必须再次从 1 开始，而不是从其他值开始。
回答by RobertB922
I know this is late, but I am going through this same challenge in zybooks. My initial code is a little different and the answers above were a little off from what the IDE was testing for. So I decided to copy and paste my code in case anyone needs a little help with this challenge.
我知道这已经晚了，但我正在 zybooks 中经历同样的挑战。我的初始代码有点不同，上面的答案与 IDE 测试的内容略有不同。所以我决定复制并粘贴我的代码，以防有人需要帮助来解决这个挑战。
import java.util.Scanner;
public class NestedLoops {
public static void main (String [] args) {
Scanner scnr = new Scanner(System.in);
int numRows;
int numColumns;
int currentRow;
int currentColumn;
char currentColumnLetter;
numRows = scnr.nextInt(); // user input for how many rows
numColumns = scnr.nextInt(); // user input for many columns
/* Your solution goes here */
currentRow = 0; // Must be intialized to 0 or a "2" will print before "1"
while (currentRow < numRows) { // Intialized the loop
currentRow++; // increments the currentRow
currentColumnLetter = 'A'; // Sets the first column to char 'A'
currentColumn = 1; // Define to intialize inner loop
while (currentColumn <= numColumns) { // Will initial for any positive input 1 +
System.out.print(currentRow); // Asked specifically for 2 printouts
System.out.print(currentColumnLetter + " "); // 2nd printout with space at end.
currentColumnLetter++; // increments the Letter
currentColumn++; // increments the column
}
}
System.out.println("");
}
}
I hope this helps anyone needing a little help with this assignment.
我希望这可以帮助任何需要帮助完成这项任务的人。
回答by TimRCM
Here's what I came up with for this particular ZyBooks challenge (I used my own iterables instead of their pre-defined ones out of habit):
这是我为这个特殊的 ZyBooks 挑战想出的东西（出于习惯，我使用了自己的可迭代对象而不是他们预先定义的可迭代对象）：
import java.util.Scanner;
public class NestedLoops {
public static void main (String [] args) {
Scanner scnr = new Scanner(System.in);
int numRows;
int numColumns;
int currentRow;
int currentColumn;
char currentColumnLetter;
numRows = scnr.nextInt();
numColumns = scnr.nextInt();
for (int i = 1; i <= numRows; i++) {
currentColumnLetter = 'A';
for (int x = 1; x <= numColumns; x++) {
System.out.print(i);
System.out.print(currentColumnLetter + " ");
currentColumnLetter++;
}
}
System.out.println("");
}
}
