Question

c#

code working but output not right, I need to output all numbers like :

Prime factors of 4 are: 2 x 2 here is just 2

Prime factors of 7 are: 7

Prime factors of 30 are: 2 x 3 x 5

Prime factors of 40 are: 2 x 2 x 2 x 5 here is just 2,5

Prime factors of 50 are: 2 x 5 x 5 here is just 2,5

1) How I can fix it

2)I need few unit tests for code

using System;

namespace PrimeFactor
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter a number greater than 1: ");
  
int entry =Convert.ToInt32(Console.ReadLine());
int num = entry;
int testFactor = 1;
string primeString = "";
while (++testFactor <= num)
{
primeString += (num % testFactor == 0) ? " " + testFactor : "";

while (num % testFactor == 0) num /= testFactor;

}
Console.WriteLine("The prime factors of " + entry + " are:" + primeString);
Console.ReadKey();
}

}
  
}

Answer 1

Program

using System;

namespace PrimeFactor
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter a number greater than 1: ");
  
int entry =Convert.ToInt32(Console.ReadLine());
int num = entry;
int testFactor = 1;
string primeString = "";
while (++testFactor <= num)
{
while (num % testFactor == 0)
{
primeString +=" " + testFactor ;
num/= testFactor ;

}

}
Console.WriteLine("The prime factors of " + entry + " are:" + primeString);
Console.ReadKey();
}

}
  
}

Sample output

Enter a number greater than 1:                                                                                                

4                                                                                                                             

The prime factors of 4 are: 2 2

Enter a number greater than 1:                                                                                                

7

The prime factors of 7 are: 7

Enter a number greater than 1:                                                                                                

40

The prime factors of 40 are: 2 2 2 5