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C Program to Check Prime or Armstrong Number Using User-defined Function

To understand this example, you should have the knowledge of the following C programming topics:

    Visit these pages to learn to check whether a number is

    Example: Check Prime and Armstrong

    Output

    Enter a positive integer: 407
407 is not a prime number.
407 is an Armstrong number.

    In this program, two user-defined functions checkPrimeNumber() and checkArmstrongNumber() are created.

    The checkPrimeNumber() function returns:

    • 1 if the number entered by the user is a prime number.
    • 0 if the number entered by the user is not a prime number.

    Similarly, checkArmstrongNumber() function returns:

    • 1 if the number entered by the user is an Armstrong number.
    • 0 if the number entered by the user is not an Armstrong number.

    Note: In checkPrimeNumber() and checkArmstrongNumber() functions, the flag variables are the return value of the functions.

    In main(), the flag variable stores the values returned by checkPrimeNumber() and checkArmstrongNumber().

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