Question

Everything else works except the range, I only want the numbers entered to be in between 2-70 but I can enter 700 for some reason. How can I make the limit work? (This is in C#)

namespace Prime_Numbers

{

class Program

{

static void Main(string[] args)

{

int limit; // Declare limit as an int as we do not need double.

Console.WriteLine("*****************************\nPRIME NUMBERS UP TO 25\n*****************************");

Console.Write("Enter a limit to the prime numbers you want displayed: ");

while (true) {

string input = Console.ReadLine(); // Convert number to a string.

Int32.TryParse(input, out limit);

if (!Int32.TryParse(input, out limit)) // See if we can parse the 'text' string. If False:

{

Console.WriteLine("Input must be a whole number. Please try again.");

}

else if (limit <= 70 || limit >= 2) // If True run the program:

{

Console.WriteLine("Calculating...");

for (int i = 1; i <= limit; i++) // Main loop for the prime number rows.

{

if (checkPrime(i))

{

for (int j = 0; j < i; j++) //For space after "X" has printed.

{

Console.Write("*");

}

Console.WriteLine(" " + i); // Adds prime number onto string output.

}

}

break;

}

  

else // If the number is out of range:

{

Console.WriteLine("The value entered must be between 2 and 70.");

}

}

Console.ReadKey();

}

static bool checkPrime(int n) // Create function to check for prime values.

{

// Check if n is 0 or 1.

if (n == 0 || n == 1)

{

return false;

}

else

{

// Loop from 2 to n / 2,

for (int i = 2; i <= n / 2; i++)

{

// If any number is divisible by i then it is not a prime number

// Assign the result of a boolean expression to n.

if (n % i == 0)

{

return false;

}

}

return true;

} //end of else

}

}

}

Answer 1

Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Prime_Numbers
{
class Program
{
static void Main(string[] args)
{
int limit; // Declare limit as an int as we do not need double.
Console.WriteLine("*****************************\nPRIME NUMBERS UP TO 25\n*****************************");
Console.Write("Enter a limit to the prime numbers you want displayed: ");
while (true)
{
string input = Console.ReadLine(); // Convert number to a string.
Int32.TryParse(input, out limit);
if (!Int32.TryParse(input, out limit)) // See if we can parse the 'text' string. If False:
{
Console.WriteLine("Input must be a whole number. Please try again.");
}
else if (limit <= 70 && limit >= 2) // If True run the program:
{
Console.WriteLine("Calculating...");
for (int i = 1; i <= limit; i++) // Main loop for the prime number rows.
{
if (checkPrime(i))
{
for (int j = 0; j < i; j++) //For space after "X" has printed.
{
Console.Write("*");
}
Console.WriteLine(" " + i); // Adds prime number onto string output.
}
}
break;
}

else // If the number is out of range:
{
Console.WriteLine("The value entered must be between 2 and 70.");
}
}
Console.ReadKey();
}
static bool checkPrime(int n) // Create function to check for prime values.
{
// Check if n is 0 or 1.
if (n == 0 || n == 1)
{
return false;
}
else
{
// Loop from 2 to n / 2,
for (int i = 2; i <= n / 2; i++)
{
// If any number is divisible by i then it is not a prime number
// Assign the result of a boolean expression to n.
if (n % i == 0)
{
return false;
}
}
return true;
} //end of else
}
}
}

output

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