# C 程序：檢查數字是否為回文數 > 原文： [https://beginnersbook.com/2015/02/c-program-to-check-if-a-number-is-palindrome-or-not/](https://beginnersbook.com/2015/02/c-program-to-check-if-a-number-is-palindrome-or-not/) 如果我們反轉數字，它也保持不變，該數字也稱為回文數。例如，12321 是回文數，因為如果我們反轉它的數字它仍然是相同的。在本文中，我們共享了兩個 C 程序來檢查輸入數字是否為回文數。 1）使用`while`循環 2）使用遞歸。 #### 程序 1：使用`while`循環檢查回文 ```c /* Program to check if a number is palindrome or not * using while loop */ #include <stdio.h> int main() { int num, reverse_num=0, remainder,temp; printf("Enter an integer: "); scanf("%d", &num); /* Here we are generating a new number (reverse_num) * by reversing the digits of original input number */ temp=num; while(temp!=0) { remainder=temp%10; reverse_num=reverse_num*10+remainder; temp/=10; } /* If the original input number (num) is equal to * to its reverse (reverse_num) then its palindrome * else it is not. */ if(reverse_num==num) printf("%d is a palindrome number",num); else printf("%d is not a palindrome number",num); return 0; } ``` **輸出：**  #### 程序 2：使用遞歸檢查回文 ```c #include<stdio.h> int check_palindrome(int num){ static int reverse_num=0,rem; if(num!=0){ rem=num%10; reverse_num=reverse_num*10+rem; check_palindrome(num/10); } return reverse_num; } int main(){ int num, reverse_num; printf("Enter a number: "); scanf("%d",&num); reverse_num = check_palindrome(num); if(num==reverse_num) printf("%d is a palindrome number",num); else printf("%d is not a palindrome number",num); return 0; } ``` **輸出：**