平方数 Java
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square numbers Java
提问by laish138
"An array is used to store ten integer numbers. Write a Java program that determines and print the square numbers which are also odd numbers from the given array."
“一个数组用于存储十个整数。编写一个 Java 程序来确定和打印平方数，这些平方数也是给定数组中的奇数。”
The problem I have is how to figure out if the number in the array is a square number. I tried this way but it's not correct!
我遇到的问题是如何确定数组中的数字是否为平方数。我试过这种方式，但它不正确！
import java.math.*;
public class JavaApplication43 {
public static void main(String[] args) {
int[] no = {22, 44, 25, 89, 81, 55, 23, 25, 55};
for (int i = 0; i < no.length; i++) {
int x = no[i];
double y;
if (x % 2 != 0) {
y = Math.sqrt(x);
if (x == (Math.pow(y, 2)))
System.out.println(no[i]);
}
}
}
}
This is the output it gives me
这是它给我的输出
run:
25
81
55
25
55
55is there too that means this method I used is not successful!
55是不是也就是我用的这个方法不成功！
回答by Konstantin Yovkov
You could just do:
你可以这样做：
for (int i = 0; i < no.length; i++) {
int x = no[i];
if (x % 2 == 0) continue;
int y = (int) Math.sqrt(x);
if (x == y * y) {
System.out.println(x);
}
}
回答by Peter Lawrey
You can determine if a number is a square by checking if its square root is an integer.
您可以通过检查数字的平方根是否为整数来确定数字是否为正方形。
double sqrt = Math.sqrt(x);
long sqrt2 = Math.round(sqrt);
if (Math.abs(sqrt - sqrt2) / sqrt < 1e-15)
// we have a square.
If you know xis an intyou shouldn't get a rounding error and you can do
如果你知道x是一个，int你不应该得到一个舍入错误，你可以这样做
int x = ...
double sqrt = Math.sqrt(x);
if ((int) sqrt == sqrt)
// we have a square.
回答by Isuru
hope this will be much easier,
希望这会容易得多，
if((arr[i]%2 != 0) & (Math.sqrt(arr[i])%1 == 0)){
System.out.println(arr[i]);
}
In here inside if condition first I check whether number is an odd number by taking modulus division and the 2nd condition check whether number is a perfect square. First I get the square root of given number and then take the modulus division by 1 and check whether it's equal to 0. If number is a perfect square, square root of that number is an integer, when I take the modulus division of an integer answer should be equal to 0.
在这里，如果条件首先我通过取模除法检查数字是否为奇数，第二个条件检查数字是否为完全平方数。首先我得到给定数的平方根，然后取模数除以 1 并检查它是否等于 0。如果数是完全平方数，则该数的平方根是整数，当我取整数的模数除法时答案应该等于 0。
