60 lines
1.6 KiB
C#
60 lines
1.6 KiB
C#
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using System;
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public class Functions
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{
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public static long Factorial(int n)
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{
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// Test for invalid input.
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if ((n < 0) || (n > 20))
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{
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return -1;
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}
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// Calculate the factorial iteratively rather than recursively.
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long tempResult = 1;
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for (int i = 1; i <= n; i++)
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{
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tempResult *= i;
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}
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return tempResult;
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}
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}
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class MainClass
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{
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static int Main(string[] args)
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{
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// Test if input arguments were supplied.
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if (args.Length == 0)
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{
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Console.WriteLine("Please enter a numeric argument.");
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Console.WriteLine("Usage: Factorial <num>");
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return 1;
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}
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// Try to convert the input arguments to numbers. This will throw
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// an exception if the argument is not a number.
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// num = int.Parse(args[0]);
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int num;
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bool test = int.TryParse(args[0], out num);
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if (!test)
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{
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Console.WriteLine("Please enter a numeric argument.");
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Console.WriteLine("Usage: Factorial <num>");
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return 1;
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}
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// Calculate factorial.
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long result = Functions.Factorial(num);
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// Print result.
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if (result == -1)
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Console.WriteLine("Input must be >= 0 and <= 20.");
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else
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Console.WriteLine($"The Factorial of {num} is {result}.");
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return 0;
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}
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}
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// If 3 is entered on command line, the
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// output reads: The factorial of 3 is 6.
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