How to Determine if a Number is Prime in C?

Determining Prime Numbers in C

To ascertain whether a given integer is prime, let's start by outlining the steps involved:

1. Initialize a loop variable i to 2.
2. Test if i is less than the input number number.
3. Check if number modulo i equals zero, indicating potential non-primality.
4. Handle the exception case where i equals number, which cannot disprove primality.
5. Increment i and repeat steps 2-4.
6. Return true (or 1) if no divisors were found, indicating the number is prime; else, return false (or 0).

Now, let's translate this algorithm into C code:

int IsPrime(unsigned int number) {
    if (number <= 1) return 0; // Handle special cases
    unsigned int i;
    for (i = 2; i*i <= number; i++) {
        if (number % i == 0) return 0; // Number has divisors
    }
    return 1; // No divisors found, number is prime
}

This function follows the outlined steps:

• It handles negative and special cases (0 and 1 are not prime).
• It iterates through potential divisors up to the square root of number.
• It efficiently tests for exact divisors.

While this method is not optimized for performance, it provides a clear and comprehensible solution for determining prime numbers in C.

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