Simple class for converting numbers without crashing the program for educational stuff.

Cynum.class.cs

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

namespace CyLib {
    /**
     * @class Cynum
     * @name Cynum
     * @desc Convert different number input and output
     *       using System.Text.RegularExpressions
     * @author Sven Gehring
     * @copyright 2014+ Sven Gehring
     */
    public class Cynum {

        private Regex patternInteger = new Regex(@"[0-9]{1,}");                         // Match a stirng of numbers
        private Regex patternDouble  = new Regex(@"\.?[0-9]{1,}(\.[0-9]{1,})?");        // Match a string of numbers with or without dots
        private Regex patternEngnum  = new Regex(@"\.?[0-9]{1,}[A-z]?([0-9]{1,})?");    // Match a string of numbers, characters and dots
        private Regex patternEngchar = new Regex(@"(f|p|n|u|m|k|M|G){1}");              // Match the allowed suffix characters



        /**
         * @method getInteger
         * @name Get Integer
         * @alias 'Ganzzahl'
         * @desc Try to convert an input string to an integer
         * @param {string} input - The given input string
         * @return {int} output - The converted integer
         */
        public int getInteger(string input) {
            int output;

            if (this.patternInteger.IsMatch(input)) {
                if (Int32.TryParse(input, out output)) {
                    return output;
                }
            }

            return 0;
        }


        /**
         * @method getDouble
         * @name Get Double
         * @alias 'Bruchzahl'
         * @desc Try to convert an input string to a double
         * @param {string} input - The given input string
         * @return {double} output - The converted double
         */
        public double getDouble(string input) {
            double output;

            if (this.patternDouble.IsMatch(input)) {
                if (Double.TryParse(input, out output)) {
                    return output;
                }
            }

            return 0;
        }


        /**
         * @method getEngnum
         * @name Get Engineering number
         * @alias 'Engnum'
         * @desc Try to convert an engineering number to a double
         * @param {string} input - The given input string
         * @return {double} output - The converted double
         */
        public double getEngnum(string input) {
            double output;
            char suffix = 'x';

            char[] suffixlist = { 'f', 'p', 'n', 'u', 'm', 'k', 'M', 'G', 'x' };
            double[] multiplier = { 0.000000000000001, 0.000000000001, 0.000000001, 0.000001, 0.001, 1000, 1000000, 1000000000, 1 };

            if (this.patternEngnum.IsMatch(input)) {
                foreach (Match match in this.patternEngchar.Matches(input)) {
                    suffix = Convert.ToChar(match.Value);
                }
                input = Regex.Replace(input, @"(f|p|n|u|m|k|M|G){1}", ".");
                input = input.TrimEnd('.');
                output = this.getDouble(input);
                output *= multiplier[(Array.IndexOf(suffixlist, suffix))];

                return output;
            }

            return 0;
        }


        /**
         * @method setEngnum
         * @name Set Engineering number
         * @alias 'EngAusgabe'
         * @desc Try to convert a double into an engineering number
         * @param {double} input - The given double
         * @return {string} output - The converted engineering string
         */
        public string setEngnum(double input) {
            string output = "";

            char[] suffixlist = { 'f', 'p', 'n', 'u', 'm', ' ', 'k', 'M', 'G' };
            double[] multiplier = { 0.000000000000001, 0.000000000001, 0.000000001, 0.000001, 0.001, 1, 1000, 1000000, 1000000000, Double.PositiveInfinity };

            for (int i = 0; i < 9; i++) {
                if (input >= multiplier[i] && input < multiplier[(i + 1)]) {
                    output = Convert.ToString(input / multiplier[i]) + suffixlist[i];
                }
            }

            return output;
        }
    }
}