var carID = taxBDO.Customer_Id;
Customer customerInDb = (from p in TaxEnitites.Customers
where p.Customer_Id == carID
select p).FirstOrDefault();
if (customerInDb.Date_Taxed < 365)
{
}
I have retrieve a date from my db that I have set up, however I can not figure out to use an if statement t use this date from my database to check if this date is more that a year ago,
any help would be appreciated
Thanks
You can add negative one years to today and compare:
customerInDb.Date_Taxed < DateTime.Now.AddYears(-1)
Yes. You can compute a timespan between now and then and fetch the total number of days.
DateTime.Now.Subtract(customerInDb.Date_Taxed).TotalDays > 365
Crowcoder has already given a solution which will work in most cases.
But, dateTime.Now has the Time component as well! So, if
customerInDb.Date_Taxed = {15/11/2014 00:05:30}
DateTime.Now = {15/11/2015 00:22:30}
Then
Date_Taxed < DateTime.Now.AddYears(-1) => true
Though it's on the same date last year. And this calculation will depend on the current time, so you'll get different results at different time of the day.
If you want this, then fine. Else, you can compare just the Date part as
var isMoreThanYearAgo = customerInDb.Date_Taxed.Date < DateTime.Now.AddYears(-1).Date;
Also, check customerInDb for null before you call this, as you are getting this as a result of FirstOrDefault().
I am developping an application where a user can download various reports. There is one report per month and each report is called "YYYY-MM.txt". An user can only download files of the last 18 months.
I have written a function that takes in parameter a list of filespath and then downloading them to the client. My problem is how to add files in this list, basically how can I check if a file is in the last 18 months, knowing that I have his year and month, and the current year and month.
This is what I have :
//just for test, supposed that theses values were extracted from the report of august 2014.
string fileYear = "2014";
string fileMonth = "08";
string currentYear = DateTime.Now.Year.ToString();
string currentMonth = DateTime.Now.Month.ToString();
How can I compare fileYear and fileMonth with currentYear and currentMonth to know if the report correspond to a month of the last 18.
Thanks in advance for your help
Here's how I would do it.
int fileYear = int.Parse(fileName.Substring(0,4));
int fileMonth = int.Parse(fileName.Substring(5,2));
DateTime oldestDate = DateTime.Now.AddMonths(-18);
int oldestYear = oldestDate.Year;
int oldestMonth = oldestDate.Month;
if(fileYear > oldestYear || (fileYear == oldestYear && fileMonth >= oldestMonth))
{
// This file is within 18 months.
}
This means that if today is 12-31-2014 it will include files back to 2013-06.txt. If needed you can also put an upper bounds check in case you could have files with future dates.
EDIT
The other alternative is to create a DateTime from the file name to compare. Here's how I would do that to ensure I'm comparing the last day of the file's month
int fileYear = int.Parse(fileName.Substring(0,4));
int fileMonth = int.Parse(fileName.Substring(5,2));
DateTime fileDate = new DateTime(fileYear, fileMonth, 1).AddMonths(1).AddDays(-1);
DateTime oldestDate = DateTime.Now.AddMonths(-18);
if(fileDate.Date >= oldestDate.Date)
{
// This file is within 18 months.
}
You could do something like this:
https://dotnetfiddle.net/VORvZr
using System;
public class Program
{
public static void Main()
{
DateTime fileDate = new DateTime(2013, 5, 1);
DateTime fileDateNewer = new DateTime(2014, 1, 1);
GetMonthDifference(fileDate);
GetMonthDifference(fileDateNewer);
}
public static void GetMonthDifference(DateTime fileDate)
{
DateTime currentDate = DateTime.Now;
DateTime eighteenMonthsAgo = currentDate.AddMonths(-18);
if (eighteenMonthsAgo > fileDate)
Console.WriteLine("{0} is greater than or equal to 18 months ago", fileDate);
else
Console.WriteLine("{0} is less than 18 months ago", fileDate);
}
}
Note that if you can, you always want to try to work with objects that most closely represent your data. E.g. if working with years you should work with a numeric type rather than string type. In this case, working with dates.
EDIT:
as comments posted on the other answers pointed out, you would have some room for error depending on the day the file was uploaded/created if it's right around the 18 month mark. Something you could potentially do is get the actual file creation date (assuming you are the system creating the file and the date of the file creation coincides with the month the data belongs. You can get a files creation date as such:
string fullFilePathAndName = #""; // wherever your file is located
FileInfo fi = new FileInfo(fullFilePathAndName);
DateTime fileCreateDate = fi.CreationTime
*(This is for ISV database so I am kind of reverse engineering this and cannot change) ...
How can I do the following date to int (visa/versa) conversion in C# ...
So Say the Date is:
5/17/2012
it gets converted to int
77207
in the database.
At first I thought this was a Julian date however it does not appear to be the case. I was fooling around with the method from Julian Date Question however this does not match up.
var date = ConvertToJulian(Convert.ToDateTime("5/17/2012"));
Console.WriteLine(date);
public static long ConvertToJulian(DateTime Date)
{
int Month = Date.Month;
int Day = Date.Day;
int Year = Date.Year;
if (Month < 3)
{
Month = Month + 12;
Year = Year - 1;
}
long JulianDay = Day + (153 * Month - 457)
/ 5 + 365 * Year + (Year / 4) -
(Year / 100) + (Year / 400) + 1721119;
return JulianDay;
}
Outputs 2456055 //Should be 77207
I've been using this SQL to do the conversion:
SELECT Convert(date, CONVERT(CHAR,DATEADD(D, 77207, '1800-12-28'),101))
and it appears to be accurate. How could I do this conversion in C# ? And can someone edify me as to what standard this is based on or is it simply a random conversion. Thanks in advance.
//TO int
var date = new DateTime(1800,12,28,0,0,0);
var daysSince = (DateTime.Now-date).Days;
//FROM int
var date = new DateTime(1800, 12, 28, 0, 0, 0);
var theDate = date.AddDays(77207);
This appears to be a Clarion Date:
the number of days that have elapsed since December 28, 1800
Allegedly to, Display Clarion Dates In Excel it only takes
subtracting 36161 from the value and formatting it as a date
If it is a linear formula, you should be able to calculate formula in the form of y=mx+b. You would need a minimum of two data points.
Here is the vb.net Code I use to convert Clarion Date to Julian Date:
Dim ldblDaysToSubtract As Double = 36161.0
mclsRevEmployeeRecd.BirthDate(istrBirthDate:=(CDbl(E1Row.Item("BIRTH_DT")) - ldblDaysToSubtract).ToString)
mstrBirthDate = Format(CDate(Date.FromOADate(CDbl(istrBirthDate)).ToString), "MM/dd/yyyy")
I have a query that is calling an Oracle DB from C#. I want to write the query to get data that is, at most, 5 years old.
I currently have a hard coded value for public const int FIVE_YEARS_IN_DAYS = 1825;
But, this isn't correct because of leap years. Is there a function that will give me the correct number of days in the preceeding 5 years?
I think you want this:
DateTime now = DateTime.Now;
now.AddYears(-5).Subtract( now ).Days
DateTime now = DateTime.Now;
TimeSpan fiveYears = now.Subtract(now.AddYears(-5));
int numberOfDaysInLastFiveYears = fiveYears.Days;
This will correctly account for leap years. Doing this right now yields 1,826 days.
This is a question of best practices. I have a utility that takes in a two digit year as a string and I need to convert it to a four digit year as a string. right now I do
//DOB's format is "MMM (D)D YY" that first digit of the day is not there for numbers 1-9
string tmpYear = rowIn.DOB.Substring(rowIn.DOB.Length - 3, 2); //-3 because it is 0 indexed
if (Convert.ToInt16(tmpYear) > 50)
tmpYear = String.Format("19{0}", tmpYear);
else
tmpYear = String.Format("20{0}", tmpYear);
I am sure I am doing it horribly wrong, any pointers?
The .NET framework has a method that does exactly what you want:
int fourDigitYear = CultureInfo.CurrentCulture.Calendar.ToFourDigitYear(twoDigitYear)
That way you will correctly adhere to current regional settings as defined in Control Panel (or group policy):
Given that there are people alive now born before 1950, but none born after 2010, your use of 50 as the flipping point seems broken.
For date of birth, can you not set the flip point to the 'year of now' (i.e. 10) in your app? Even then you'll have problems with those born before 1911...
There's no perfect way to do this - you're creating information out of thin air.
I've assumed DOB = date-of-birth. For other data (say, maturity of a financial instrument) the choice might be different, but just as imperfect.
You can also use the DateTime.TryParse method to convert your date. It uses the current culture settings to define the pivot year (in my case it is 2029)
DateTime resultDate;
Console.WriteLine("CultureInfo.CurrentCulture.Calendar.TwoDigitYearMax : {0}", System.Globalization.CultureInfo.CurrentCulture.Calendar.TwoDigitYearMax);
DateTime.TryParse("01/01/28", out resultDate);
Console.WriteLine("Generated date with year=28 - {0}",resultDate);
DateTime.TryParse("01/02/29",out resultDate);
Console.WriteLine("Generated date with year=29 - {0}", resultDate);
DateTime.TryParse("01/03/30", out resultDate);
Console.WriteLine("Generated date with year=30 - {0}", resultDate);
The output is:
CultureInfo.CurrentCulture.Calendar.TwoDigitYearMax : 2029
Generated date with year=28 - 01/01/2028 00:00:00
Generated date with year=29 - 01/02/2029 00:00:00
Generated date with year=30 - 01/03/1930 00:00:00
If you want to change the behavior you can create a culture with the year you want to use as pivot. This thread shows an example
DateTime.TryParse century control C#
But as martin stated, if you want to manage a time period that spans more than 100 year, there is no way to do it with only 2 digits.
I think Java has a good implementation of this:
http://java.sun.com/javase/6/docs/api/java/text/SimpleDateFormat.html#year
People rarely specify years far into the future using a two-digit code. The Java implementation handles this by assuming a range of 80 years behind and 20 years ahead of the current year. So right now, 30 would be 2030, while 31 would be 1931. Additionally, this implementation is flexible, modifying its ranges as time goes on, so that you don't have to change the code every decade or so.
I just tested, and Excel also uses these same rules for 2-digit year conversion. 1/1/29 turns into 1/1/2029. 1/1/30 turns into 1/1/1930.
The implementation of
System.Globalization.CultureInfo.CurrentCulture.Calendar.ToFourDigitYear
is
public virtual int ToFourDigitYear(int year)
{
if (year < 0)
throw new ArgumentOutOfRangeException("year", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
if (year < 100)
return (this.TwoDigitYearMax / 100 - (year > this.TwoDigitYearMax % 100 ? 1 : 0)) * 100 + year;
else
return year;
}
Hope this helps!
It might be smarter to check tmpYear > currentYear%100. If it is, then it's 19XX, otherwise 20XX.
This solution we use for Expiration Dates, the user enters MM and YY into separate fields. This results in dates being the 31st or 30th and 28th or 29th also for February.
/// <summary>
/// Creates datetime for current century and sets days to end of month
/// </summary>
/// <param name="MM"></param>
/// <param name="YY"></param>
/// <returns></returns>
public static DateTime GetEndOfMonth(string MM, string YY)
{
// YY -> YYYY #RipVanWinkle
// Gets Current century and adds YY to it.
// Minus 5 to allow dates that may be expired to be entered.
// eg. today is 2017, 12 = 2012 and 11 = 2111
int currentYear = DateTime.Now.Year;
string thisYear = currentYear.ToString().Substring(0, 2) + YY;
int month = Int32.Parse(MM);
int year = Int32.Parse(thisYear);
if ((currentYear - 5) > year)
year += 100;
return new DateTime(year, month, DateTime.DaysInMonth(year, month));
}
This Method can convert the credit card last two year digits to four year
private static int ToFourDigitYear(int year)
{
string stringYear = year.ToString("00");
if (stringYear.Length == 2)
{
int currentYear = DateTime.Now.Year;
string firstTwoDigitsOfCurrentYear = currentYear.ToString().Substring(0, 2);
year = Convert.ToInt32(firstTwoDigitsOfCurrentYear + stringYear);
if (year < currentYear)
year = year + 100;
}
return year;
}
Out of curiosity, from where do you get this data? From a form? In that case; I would simply ask the user to fill in (or somehow select) the year with four digits or get the users age and month/day of birth, and use that data to figure out what year they were born. That way, you wouldn't have to worry about this problem at all :)
Edit: Use DateTime for working with this kind of data.
Try this simple code
//Invoke TextBoxDateFormat method with date as parameter.
Method
public void TextBoxDateFormat(string str1)
{
// Takes the current date format if MM/DD/YY or MM/DD/YYYY
DateTime dt = Convert.ToDateTime(str1);
//Converts the requested date into MM/DD/YYYY and assign it to textbox field
TextBox = String.Format("{0:MM/dd/yyyy}", dt.ToShortDateString());
//include your validation code if required
}
Had a similar issue, and came up with this... HTH!
value = this.GetDate()
if (value.Length >= 6)//ensure that the date is mmddyy
{
int year = 0;
if (int.TryParse(value.Substring(4, 2), out year))
{
int pastMillenium = int.Parse(DateTime.Now.ToString("yyyy").Substring(0, 2)) - 1;
if (year > int.Parse(DateTime.Now.ToString("yy")))//if its a future year it's most likely 19XX
{
value = string.Format("{0}{1}{2}", value.Substring(0, 4), pastMillenium, year.ToString().PadLeft(2, '0'));
}
else
{
value = string.Format("{0}{1}{2}", value.Substring(0, 4), pastMillenium + 1, year.ToString().PadLeft(2, '0'));
}
}
else
{
value = string.Empty;
}
}
else
{
value = string.Empty;
}
My answer will not match your question but for credit cards I just add 2 digits of current year
private int UpconvertTwoDigitYearToFour(int yearTwoOrFour)
{
try
{
if (yearTwoOrFour.ToString().Length <= 2)
{
DateTime yearOnly = DateTime.ParseExact(yearTwoOrFour.ToString("D2"), "yy", null);
return yearOnly.Year;
}
}
catch
{
}
return yearTwoOrFour;
}
If you calculate for a person he will probably not be more than 100 years...
Eg: 751212
var nr = "751212";
var century = DateTime.Now.AddYears(-100).Year.ToString().Substring(0, 2);
var days = (DateTime.Now - DateTime.Parse(century + nr)).Days;
decimal years = days / 365.25m;
if(years>=99)
century = DateTime.Now.Year.ToString().Substring(0, 2);
var fullnr = century+nr;
To change a 2-digit year to 4-digit current or earlier -
year = year + (DateTime.Today.Year - DateTime.Today.Year%100);
if (year > DateTime.Today.Year)
year = year - 100;
My two cents,
Given an age range=[18, 100+], two digits year=90, I can do
current year - twoDigitsYear = 2018 - 90 = 1928, I got 19, 28
hence 19 is the first two digits of year of born, and 28 is the age, which is
year=1990, age=28
But it won't work when age 0 and 100 both included in the range, same to some of the other answers here.
Based on above solutions, here is mine, i used in android while using java
it takes current year in two digit format then checks for if input
year length is equal to 2, if yes then it get current year and from
this year it splits first two digits of century, then it adds this
century with year user input. to make it 4 digit year.
public static int getConvertedYearFromTwoToFourDigits(String year) {
if (year.length() == 2) {
int currentYear = Calendar.getInstance().get(Calendar.YEAR);
String firstTwoDigitsOfCurrentYear = String.valueOf(currentYear).substring(0, 2);
year = firstTwoDigitsOfCurrentYear + year;
}
return Integer.parseInt(year);
}
int fYear = Convert.ToInt32(txtYear.Value.ToString().Substring(2, 2));
My answer will not match your question but for credit cards I just add 2 digits of current year
private int UpconvertTwoDigitYearToFour(int yearTwoOrFour)
{
try
{
if (yearTwoOrFour.ToString().Length <= 2)
{
DateTime yearOnly = DateTime.ParseExact(yearTwoOrFour.ToString("D2"), "yy", null);
return yearOnly.Year;
}
}
catch
{
}
return yearTwoOrFour;
}