In this post, we will learn** how to find the prime factors of a number using C++** Programming language.

Suppose the user enters a number** 18**, then it’s prime factors will be **2** and **3**. We will find the prime factors using the following methods:

- Using While Loop
- Using for Loop

So, without further ado, let’s begin this tutorial.

**C++ Program to Find Prime Factors of a Number**

// C++ Program to Find Prime Factors of a Number #include <iostream> using namespace std; int main(){ int num, i = 1, j, count; // Asking for input cout << "Enter any number to find prime factors: "; cin >> num; while (i <= num){ count = 0; if (num % i == 0){ j = 1; while (j <= i){ if (i % j == 0){ count++; } j++; } if (count == 2){ cout << i << " is a prime factor of " << num << endl; } } i++; } return 0; }

**Output**

```
Enter any number to find prime factors: 15
3 is a prime factor of 15
5 is a prime factor of 15
```

**How Does This Program Work ?**

int num, i = 1, j, count;

In this program, we have declared** four int data type** variables named **num**,** i**,** j** and **count**.

// Asking for input cout << "Enter any number to find prime factors: "; cin >> num;

Then, the user is asked to enter any number to find its prime factors.

while (i <= num){ count = 0; if (num % i == 0){ j = 1; while (j <= i){ if (i % j == 0){ count++; } j++; }

We have used a** while loop** to find the factors of the entered number.

if (count == 2){ cout << i << " is a prime factor of " << num << endl; }

We display the prime factors of the entered number with the help of the **cout **statement.

**C++ Program to Find Prime Factors of a Number Using For Loop**

// C++ Program to Find Prime Factors of a Number #include <iostream> using namespace std; int main(){ int num, i, j, count; // Asking for input cout << "Enter any number: "; cin >> num; for (i = 1; i <= num; i++){ count = 0; if (num % i == 0){ for (j = 1; j <= i; j++){ if (i % j == 0){ count++; } } } if (count == 2){ cout << i << " is a prime factor of " << num << endl; } } return 0; }

**Output**

```
Enter any number: 42
2 is a prime factor of 42
3 is a prime factor of 42
7 is a prime factor of 42
```

**Conclusion**

I hope after going through this post, you understand** how to find the prime factors of a number using C++ **Programming language.

If you have any doubts regarding the program, feel free to contact us in the comment section. We will be delighted to assist you.

**Also Read:**

Gurpreet Singh#include

#include

void main()

{

int num,n,a=2;

cout<>num;

while( a<=num)

{

if(num%a==0)

{

num=num/a;

cout<<"\n "<<a;

}

else

{

a=a+1;

}

}

}

I think this works as well

Gurpreet Singh#include

#include

void main()

{

int num,n,a=2;

cout<>num;

while( a<=num)

{

if(num%a==0)

{

num=num/a;

cout<<"\n "<<a;

}

else

{

a=a+1;

}

}

}