英文:
Questions about copyEven in java
问题
以下是您的代码的翻译部分：
public static int[] copyEven(int[] nums) {
int n = nums.length;
int a = 0;
for (int i = 0; i < n; i++) {
if (nums[i] % 2 != 0) {
a++;
}
}
int c = a;
int[] arr = new int[c];
int b = 0;
for (int j = 0; b < a; j++) {
if (nums[j] % 2 != 0) {
arr[b] = nums[j];
b++;
}
}
return arr;
}
关于您提到的问题，"the array is written to, never read from" 的意思是，代码中声明了一个新的数组 arr，但在第二个循环中，您只在循环体内将元素写入该数组，而没有在后续的代码中对该数组进行读取或使用。这可能会导致编译器给出警告或错误，因为您声明了一个数组，但似乎在后续的代码中没有使用到它。要解决这个问题，您需要确保在创建并写入数组后，代码中还需要使用该数组进行进一步的操作。
英文:
The question is as follows:
Write a Java method int[] copyEven(int[] nums) that copy elements at even indices to a new array.
It must return the new array of the correct length with those elements inside.
For example
copyEven([1, 2, 3]) → [1, 3]
copyEven([1, 2, 3, 4]) → [1, 3]
Below is my code:
public static int [] copyEven(int[] nums){
int n =nums.length;
int a=0;
for (int i=0;i<n;i++){
if (nums[i]%2 !=0){
a++;
}
int c=a;
int [] arr=new int[c];
int b=0;
for (int j=0;b<a;j++){
if (nums[j]%2 !=0){
arr[b]=nums[j];
b++;}
}
}
return arr;
}
I am just a beginner on code, and this is my first time using this website. I searched online and found that in similar questions, the number of odd numbers is provided. Thus, I plan to use a in the code to count the number of odd numbers at first, then create a new array to finish the question. However, NetBeans told me that in int [] arr=new int[c],the array is written to,never read from. I do not understand what that means. I would appreciate it very much if you can help me, thank you!
答案1
得分: 0
以下是您要翻译的内容：
在这里，您可以获得所有偶数索引处的元素。<br>根据您提供的示例，索引从1开始计数。
public static int[] copyEven(int[] nums) {
int length = nums.length;
int numberOfEvenNumbers = (length % 2 == 0) ? length / 2 : length / 2 + 1;
int[] copy = new int[numberOfEvenNumbers];
int index = 0;
for (int i = 0; i < nums.length; i += 2) {
copy[index] = nums[i];
index++;
}
return copy;
}
英文:
Here you can get all elements at even indices. <br> Indexing started from 1 as your given examples said.
public static int[] copyEven(int[] nums) {
int length = nums.length;
int numberOfEvenNumbers = (length % 2 == 0) ? length / 2 : length / 2 + 1;
int[] copy = new int[numberOfEvenNumbers];
int index = 0;
for (int i = 0; i < nums.length; i += 2) {
copy[index] = nums[i];
index++;
}
return copy;
}
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