C Exercises: Check if a number is Authomorphic or not

Last update on August 05 2025 12:55:13 (UTC/GMT +8 hours)

21. Automorphic Number Check Variants

Write a program in C to check if a number is Authomorphic or not.

Sample Solution:

C Code:

# include <stdio.h>
# include <stdlib.h>
# include <stdbool.h>

// Function to check if a number is an Automorphic Number
bool chkAutomor(int num1)
{
    int sqno = num1 * num1;  // Calculating the square of the number
    while (num1 > 0)  // Loop to compare digits of 'num1' and its square
    {
        if (num1 % 10 != sqno % 10)  // Checking if the last digits of 'num1' and its square are not equal
            return false;  // Returning false if the last digits are not equal
        num1 /= 10;  // Moving to the next digit in 'num1'
        sqno /= 10;  // Moving to the next digit in its square
    }
    return true;  // Returning true if all digits match
}

// Main function
int main()
{
    int auno;  // Variable to store the input number

    // Printing information about the program and asking for user input
    printf("\n\n Check whether a number is an Automorphic Number or not: \n");
    printf(" ------------------------------------------------------------\n");
    printf(" Input a number: ");
    scanf("%d", &auno);  // Reading input from the user

    // Checking if the entered number is an Automorphic Number using the function
    if (chkAutomor(auno))
        printf(" The given number is an Automorphic Number.\n");  // Printing if the number is an Automorphic Number
    else
        printf(" The given number is not an Automorphic Number.\n");  // Printing if the number is not an Automorphic Number

    return 0;  // Returning 0 to indicate successful execution
}

Sample Output:

Input a number: 76                                                                                           
 The given number is an Automorphic Number.

Visual Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to check if a number is automorphic by comparing its square's ending digits.
• Write a C program to verify automorphic numbers using string conversion techniques.
• Write a C program to list automorphic numbers and display the matching digit patterns.
• Write a C program to test automorphic properties for large numbers using modular arithmetic.

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