tester4

using System;
/* a helper class, Tester, begun in Lesson 5 and now extended in
Lessons 6 and 7 of intro C# console programming series found at the
following URL:
http://williammillerservices.com/windows-c-console-programming/

contains the following helper methods:
+ IsInteger()
+ IsDate()
+ IsDateAndLiesInThePast()
+ IsDateAndLiesInTheFuture()
+ GetDifferenceInYears()
+ DaysTillNextBirthday()

GitHub gist -> https://gist.github.com/kyrathasoft/98ab12cc0b18c5639ce444765d09acc1
Pastebin.com -> https://pastebin.com/e1WzzVQQ

note: to use, you would reference the file containing this code
from your primary program file. If you have the following program...

using System;
using TestInput;

namespace MyNS{
    class MyCls{
        public static void Main(){
            string sNum = "4";
            if(Tester.IsInteger(sNum)){
                Console.WriteLine("Yes, we can parse {0} to an int.", sNum);
            }
        }
    }
}

...and if above program named test.cs and below is tester.cs and in
same directory, then we'd compile like so:

csc /out:test.exe test.cs tester4.cs

Running resulting test.exe would produce: Yes, we can parse 4 to an int.

Or, we could make tester4.cs code into DLL via:
csc /t:library tester4.cs

...and then compile like so:
csc /r:tester4.dll test.cs

*/


namespace TestInput
{
    public class Tester
    {
        public static bool IsInteger(string p)
        {
            bool result = false;
            int i;

            if (int.TryParse(p, out i))
            {
                result = true;
            }

            return result;
        }

        public static bool IsDate(string p)
        {
            bool result = false;
            DateTime dt;

            if (DateTime.TryParse(p, out dt))
            {
                result = true;
            }

            return result;
        }

        public static bool IsDateAndLiesInThePast(string sDT)
        {
            bool result = false;

            if (IsDate(sDT))
            {
                DateTime dtParsed = DateTime.Parse(sDT);

                if (dtParsed < DateTime.Now)
                {
                    result = true;
                }
            }

            return result;
        }

        public static bool IsDateAndLiesInTheFuture(string sDT)
        {
            bool result = false;

            if (IsDate(sDT))
            {
                DateTime dtParsed = DateTime.Parse(sDT);

                if (dtParsed > DateTime.Now)
                {
                    result = true;
                }
            }

            return result;
        }


        public static int GetDifferenceInYears(DateTime startDate, DateTime endDate)
        {
            //Excel documentation says "COMPLETE calendar years in between dates"
            int years = endDate.Year - startDate.Year;

            if (startDate.Month == endDate.Month &&// if the start month and the end month are the same
                endDate.Day < startDate.Day// AND the end day is less than the start day
                || endDate.Month < startDate.Month)// OR if the end month is less than the start month
            {
                years--;
            }

            return years;
        }

        public static int DaysTillNextBirthday(DateTime dateOfBirth)
        {
            //full days (whole, 24-hr periods) until next birthday...
            int result = 0;
            DateTime dtToday = DateTime.Now;
            DateTime dtNextBirthday = new DateTime(dtToday.Year, dateOfBirth.Month, dateOfBirth.Day);
            TimeSpan tsDifference = dtNextBirthday - dtToday;

            if (tsDifference.Days < 0)
            {
                //already had birthday this year
                tsDifference = dtNextBirthday.AddYears(1) - dtToday;
            }
            result = tsDifference.Days;
            return result;
        }
    }
}