C program to find out the palindrome number in a range

C program to find out the palindrome numbers in a range:

In this C programming tutorial, we will learn how to find out all palindrome numbers in a range. A number is called a Palindrome number if it is equal to its reverse. For example, 141 is a palindrome number but 122 is not.

Our program will take the start number and the end number as input and it will find out all palindrome numbers between these numbers including them.

To find out a palindrome, we will reverse the number and compare it with the original number. If both numbers are equal, the number is a palindrome.

Example C program to find all palindrome numbers in a range:

The following program prints all the palindrome numbers in a user-given range:

#include <stdio.h>

int main()
{
    //1
    int startNumber;
    int endNumber;
    int i;
    int currentNumber;
    int reversedNumber;
    int rem;

    //2
    printf("Enter the first number:");
    scanf("%d", &startNumber);

    //3
    printf("Enter the second number:");
    scanf("%d", &endNumber);

    //4
    printf("Palindrome number between %d and %d are:\n", startNumber, endNumber);

    for (i = startNumber; i <= endNumber; i++)
    {
        currentNumber = i;
        reversedNumber = 0;

        //5
        while (currentNumber)
        {
            rem = currentNumber % 10;
            currentNumber = currentNumber / 10;
            reversedNumber = reversedNumber * 10 + rem;
        }

        if(i == reversedNumber){
            printf("%d ", i);
        }
    }
    return 0;
}

Download it on GitHub

Explanation:

The commented numbers in the above program denote the step numbers below:

1. First of all, create a few integer variables to use in the program.
2. Ask the user to enter the first number. Read and assign it to the startNumber variable.
3. Similarly, ask the user to enter the second number. Read and assign it to the endNumber variable.
4. To print out the palindrome numbers in this range, it uses a for loop to iterate over the numbers one by one from startNumber to endNumber.
5. Inside the loop, we are using one while loop to find out the reverse of the current number. If the reversed number is equal to the current number, it is a palindrome number. The program prints it. Else, it moves to the next value.

Sample Output:

It will print outputs as below:

Enter the first number : 10
Enter the second number : 100
Palindrome number between 10 and 100 are :
11 22 33 44 55 66 77 88 99

Enter the first number : 1000
Enter the second number : 2000
Palindrome number between 1000 and 2000 are :
1001 1111 1221 1331 1441 1551 1661 1771 1881 1991

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