C Exercises: Print all prime factors of a given number

Last update on March 20 2025 12:36:06 (UTC/GMT +8 hours)

25. Prime Factorization Variants

Write a C program to print all prime factors of a given number.

Example:
Input: n = 75
Output: All prime factors of 75 are: 3 5 5

Visual Presentation:

Sample Solution:

C Code:

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

// Main function
int main(void) {
    // Declare and initialize the variable 'n' to find its prime factors
    int n = 75; // The number for which prime factors are to be found

    printf("All prime factors of %d are: ", n); // Display the original number

    // Check if the number 'n' is greater than 0 before finding its prime factors
    if (n > 0) {
        // Extract all the factors of 2
        while (n % 2 == 0) {
            printf("2 "); // Print '2' as a prime factor
            n /= 2; // Divide 'n' by 2
        }

        // Check for odd factors starting from 3
        for (int i = 3; i <= sqrt(n); i += 2) {
            // Check if 'i' is a factor of 'n'
            while (n % i == 0) {
                printf("%d ", i); // Print 'i' as a prime factor
                n /= i; // Divide 'n' by 'i'
            }
        }

        // If 'n' is greater than 2 and has a prime factor > sqrt(n)
        if (n > 2) {
            printf("%d ", n); // Print 'n' as a prime factor
        }
    }

    return 0; // End of the main function
}

Sample Output:

All prime factors of 75 are: 3 5 5

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to print all prime factors of a given number using trial division.
• Write a C program to factorize a number and display repeated prime factors with their counts.
• Write a C program to implement prime factorization using recursion and optimized trial division.
• Write a C program to compute the prime factors and then reconstruct the original number from those factors.

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