Java中使用while和for循环的回文数程序

什么是回文数？

一个回文数 是一个在反转时保持不变的数字。例如，131。当它的数字颠倒时，它仍然是相同的数字。回文数在垂直轴上具有反射对称性。指字母颠倒后拼写相同的单词。

Java 中的回文数示例

121, 393, 34043, 111, 555, 48084

回文数示例

 LOL, MADAM

回文数算法

下面是Java中的回文数算法逻辑：

• 获取需要检查是否为回文的输入数字
• 将数字复制到一个临时变量中并反转它。
• 比较倒序数和原数。
• 如果它们相同，则数字为“回文数”
• 其他数字不是“回文数”

如何判断输入的数是否为回文数

下面是一个带有while循环的Java回文程序

package com.guru99;
 
public class PalindromeNum {
 
	public static void main(String[] args)
	{
 
		int lastDigit,sum=0,a;    
		int inputNumber=171; //It is the number  to be checked for palindrome 
 
		a=inputNumber; 
        
        // Code to reverse a number
		while(a>0)
		{   System.out.println("Input Number "+a);  
			lastDigit=a%10; //getting remainder  
			System.out.println("Last Digit "+lastDigit); 
			System.out.println("Digit "+lastDigit+ " was added to sum "+(sum*10)); 
			sum=(sum*10)+lastDigit;  
			a=a/10;
			
		}    
 
		// if given number equal to sum than number is palindrome otherwise not palindrome
		if(sum==inputNumber)    
			System.out.println("Number is palindrome ");    
		else    
			System.out.println("Number is not palindrome");    
 
	}
 
}

代码输出：

Input Number 171
Last Digit 1
Digit 1 was added to sum 0
Input Number 17
Last Digit 7
Digit 7 was added to sum 10
Input Number 1
Last Digit 1
Digit 1 was added to sum 170
Number is palindrome

使用 for 循环检查回文的程序

下面是一个使用 for 循环的回文 Java 程序

package com.guru99;
 
public class PalindromeNum {
 
	public static void main(String[] args)
	{
 
		int lastDigit,sum=0,a;    
		int inputNumber=185; //It is the number  to be checked for palindrome 
 
		a=inputNumber; 
        
        // Code to reverse a number
	for( ;a != 0; a /= 10 )
		{   System.out.println("Input Number "+a);  
			lastDigit=a%10; //getting remainder  
			System.out.println("Last Digit "+lastDigit); 
			System.out.println("Digit "+lastDigit+ " was added to sum "+(sum*10)); 
			sum=(sum*10)+lastDigit;  
			a=a/10;
			
		}    
 
		// if given number equal to sum than number is palindrome otherwise not palindrome
		if(sum==inputNumber)    
			System.out.println("Number is palindrome ");    
		else    
			System.out.println("Number is not palindrome");    
 
	}
 
}

代码输出：

Input Number 185
Last Digit 5
Digit 5 was added to sum 0
Input Number 1
Last Digit 1
Digit 1 was added to sum 50
Number is not palindrome