C++ Program to Find Prime Factor

February 8, 2021 9:55 am IST

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What is Prime Factor?

A Prime Factors of a given number is that any prime number other than 1 and itself that exactly divides the given number. For example, the prime factors of 60 is 2, 3, 5

Examples

The following table provides few examples of prime factors of a number.

Number	Prime Factors
55	5, 11
100	2, 5
186	2, 3, 31

Find Prime Factor

In the following example, we will find all the Prime factors of the given number (186).

Example

C++ Compiler

#include <iostream> using namespace std; int main() { int num = 186; int i, j; int count = 0; int flag = 0; cout << "Prime factor of " << num << ": \n"; for(i=2; i<num; i++) { // check for divisibility if(num % i == 0) { count = 0; // check for prime number for(j=1; j<=i; j++) { if(i % j == 0) count++; } if(count == 2) { flag = 1; cout << i << " "; } } } if(flag == 0) cout << "There is no Prime factor for " << num; return 0; }

Output

Prime factor of 186: 2 3 31

Find Prime Factor of any Given Number

In the following example, we will find a prime factors of any given number.

Example

C++ Compiler

#include <iostream> using namespace std; int main() { int i, j, num; cout << "Enter a (int) Number: "; cin >> num; int count = 0; int flag = 0; cout << "\nPrime factor of " << num << ": \n"; for(i=2; i<num; i++) { // check for divisibility if(num % i == 0) { count = 0; // check for prime number for(j=1; j<=i; j++) { if(i % j == 0) count++; } if(count == 2) { flag = 1; cout << i << " "; } } } if(flag == 0) cout << "There is no Prime factor for " << num; return 0; }