# 算法题：检查数字是否为回文

2021年4月16日19:52:17 发表评论 856 次浏览

## 本文概述

``````Input: N = 2002
Output: true

Input: N = 1234
Output: false``````

## C++

``````//C program to check whether a number
//is Palindrome or not.

#include <stdio.h>

/* Iterative function to reverse digits of num*/
int reverseDigits( int num)
{
int rev_num = 0;
while (num> 0) {
rev_num = rev_num * 10 + num % 10;
num = num /10;
}
return rev_num;
}

/* Function to check if n is Palindrome*/
int isPalindrome( int n)
{

//get the reverse of n
int rev_n = reverseDigits(n);

//Check if rev_n and n are same or not.
if (rev_n == n)
return 1;
else
return 0;
}

/*Driver program to test reversDigits*/
int main()
{
int n = 4562;
printf ( "Is %d a Palindrome number? -> %s\n" , n, isPalindrome(n) == 1 ? "true" : "false" );

n = 2002;
printf ( "Is %d a Palindrome number? -> %s\n" , n, isPalindrome(n) == 1 ? "true" : "false" );
return 0;
}``````

## Java

``````//Java program to check whether a number
//is Palindrome or not.

class GFG
{
/* Iterative function to reverse digits of num*/
static int reverseDigits( int num)
{
int rev_num = 0 ;
while (num> 0 ) {
rev_num = rev_num * 10 + num % 10 ;
num = num /10 ;
}
return rev_num;
}

/* Function to check if n is Palindrome*/
static int isPalindrome( int n)
{

//get the reverse of n
int rev_n = reverseDigits(n);

//Check if rev_n and n are same or not.
if (rev_n == n)
return 1 ;
else
return 0 ;
}

/*Driver program to test reversDigits*/
public static void  main(String []args)
{
int n = 4562 ;
System.out.println( "Is" + n + "a Palindrome number? -> " +
(isPalindrome(n) == 1 ? "true" : "false" ));

n = 2002 ;

System.out.println( "Is" + n + "a Palindrome number? -> " +
(isPalindrome(n) == 1 ? "true" : "false" ));

}

}

//This code is contributed
//by Hritik Raj ( ihritik )``````

## Python3

``````# Python3 program to check whether a
# number is Palindrome or not.

# Iterative function to reverse
# digits of num
def reverseDigits(num) :

rev_num = 0 ;
while (num> 0 ) :
rev_num = rev_num * 10 + num % 10
num = num //10

return rev_num

# Function to check if n is Palindrome
def isPalindrome(n) :

# get the reverse of n
rev_n = reverseDigits(n);

# Check if rev_n and n are same or not.
if (rev_n = = n) :
return 1
else :
return 0

# Driver Code
if __name__ = = "__main__" :

n = 4562

if isPalindrome(n) = = 1 :
print ( "Is" , n, "a Palindrome number? ->" , True )

else :
print ( "Is" , n, "a Palindrome number? ->" , False )

n = 2002

if isPalindrome(n) = = 1 :
print ( "Is" , n, "a Palindrome number? ->" , True )

else :
print ( "Is" , n, "a Palindrome number? ->" , False )

# This code is contributed by Ryuga``````

## C#

``````//C# program to check whether a number
//is Palindrome or not.

using System;
class GFG
{
/* Iterative function to reverse digits of num*/
static int reverseDigits( int num)
{
int rev_num = 0;
while (num> 0) {
rev_num = rev_num * 10 + num % 10;
num = num /10;
}
return rev_num;
}

/* Function to check if n is Palindrome*/
static int isPalindrome( int n)
{

//get the reverse of n
int rev_n = reverseDigits(n);

//Check if rev_n and n are same or not.
if (rev_n == n)
return 1;
else
return 0;
}

/*Driver program to test reversDigits*/
public static void  Main()
{
int n = 4562;
Console.WriteLine( "Is" + n + "a Palindrome number? -> " +
(isPalindrome(n) == 1 ? "true" : "false" ));

n = 2002;

Console.WriteLine( "Is" + n + "a Palindrome number? -> " +
(isPalindrome(n) == 1 ? "true" : "false" ));

}

}

//This code is contributed
//by Hritik Raj ( ihritik )``````

## PHP

``````<?php
//PHP program to check whether a number
//is Palindrome or not.

//Iterative function to reverse
//digits of num
function reverseDigits( \$num )
{
\$rev_num = 0;
while ( \$num> 0)
{
\$rev_num = \$rev_num * 10 +
\$num % 10;
\$num = \$num /10;
}
return \$rev_num ;
}

//Function to check if n is Palindrome
function isPalindrome( \$n )
{

//get the reverse of n
\$rev_n = reverseDigits( \$n );

//Check if rev_n and n are same or not.
if ( \$rev_n == \$n )
return 1;
else
return 0;
}

//Driver Code
\$n = 4562;
echo "Is " , \$n , " a Palindrome number? ->" ;

if (isPalindrome( \$n ) == 1)
echo "true" ;
else
echo "false" ;
echo "\n" ;

\$n = 2002;
echo "Is " , \$n , " a Palindrome number? ->" ;
if (isPalindrome(! \$n ))
echo "true" ;
else
echo "false" ;

//This code is contributed by jit_t
?>``````

``````Is 4562 a Palindrome number? -> false
Is 2002 a Palindrome number? -> true``````