Reputation: 25
I'm trying to get a factorial to be displayed as for example (factorial of 5 is 5*4*3*2*1)
I'm using a method for the factorial, but it doesn't accept the line Console.Write(i + " x ");
in my code.
Any help would be great. here is my code.
//this method asks the user to enter a number and returns the factorial of that number
static double Factorial()
{
string number_str;
double factorial = 1;
Console.WriteLine("Please enter number");
number_str = Console.ReadLine();
int num = Convert.ToInt32(number_str);
// If statement is used so when the user inputs 0, INVALID is outputed
if (num <= 0)
{
Console.WriteLine("You have entered an invalid option");
Console.WriteLine("Please enter a number");
number_str = Console.ReadLine();
num = Convert.ToInt32(number_str);
//Console.Clear();
//topmenu();
//number_str = Console.ReadLine();
}
if (num >= 0)
{
while (num != 0)
{
for (int i = num; i >= 1; i--)
{
factorial = factorial * i;
}
Console.Write(i + " x ");
Console.Clear();
Console.WriteLine("factorial of " + number_str.ToString() + " is " + factorial);
factorial = 1;
Console.WriteLine("(please any key to return to main menu)");
Console.ReadKey();
Console.Clear();
topmenu();
}
}
return factorial;
}
Thank you!
Upvotes: 0
Views: 1062
Reputation: 25370
here's a solution to consider
public static void Main()
{
Console.WriteLine("Please enter number");
int input;
while (!int.TryParse(Console.ReadLine(), out input) || input <= 0)
{
Console.WriteLine("You have enter an invald option");
Console.WriteLine("Please enter number");
}
Console.Write("Factorial of " + input + " is : ");
int output = 1;
for (int i = input; i > 0; i--)
{
Console.Write((i == input) ? i.ToString() : "*" + i);
output *= i;
}
Console.Write(" = " +output);
Console.ReadLine();
}
int.TryParse() will be beneficial for you, so the program doesn't crash if the user inputs a non-integer
also, you may want something besides an integer. Factorials get very large very fast - anything over 16 will return a wrong result.
Upvotes: 1
Reputation: 564851
The problem is that your for loop isn't using braces, so the scope is just one line.
Try adding braces appropriately:
for (int i = num; i >= 1; i--)
{
factorial = factorial * i;
Console.Write(i.ToString() + " x ");
}
Console.WriteLine("factorial of " + number_str.ToString() + " is " + factorial);
Without the braces, the i
variable only exists on the next statement (factorial = factorial * i;
), and no longer exists in scope by the time you call Console.Write
.
You will likely also want to remove the call to Console.Clear
immediately following this Write
, or you will not see it.
Upvotes: 5