# Wolfram Language™

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## Find Your Age in Days

Find out how many days old you are, and how many days until your next birthday.

### code

DateDifference["Jan 4, 1987", Today]
DateDifference[Today, "Jan 4, 2015"]

Make a website that shows days old and days until next birthday:

DaysOld[birthdate_] := DateDifference[birthdate, Today]
DaysToNextBirthday[birthdate_] := Block[{year, nextBirthday}, (* get the current year *) year = Today["Year"]; (* replace the birthday year with the year of the next birthday *) nextBirthday = DateList[birthdate]; nextBirthday[[1]] = year; If[DateDifference[Today, nextBirthday] < 0, nextBirthday[[1]] = year + 1]; (* return the number of days to the next birthday *) DateDifference[Today, nextBirthday] ]
CloudDeploy[FormFunction[ FormObject[{"date" -> <|"Interpreter" -> "Date", "Label" -> "birth date:"|>}], Style[Row[{" You are ", Style[DaysOld[#date], 18], " days old and have ", Style[DaysToNextBirthday[#date], 18], " days until your next birthday."}], FontFamily -> "Times"] &, "HTML"], Permissions -> "Public"]

### how it works

This example was live-coded at the Wolfram Research booth at SXSW, March 9, 2014.

How many days old are you?

DateDifference["Jan 4, 1987", Today]

How many days until your next birthday?

DateDifference[Today, "Jan 4, 2015"]

You can package those questions as functions. DaysOld is trivial:

DaysOld[birthdate_] := DateDifference[birthdate, Today]

DaysToNextBirthday requires a little fancy footwork to construct the date of the next birthday:

DaysToNextBirthday[birthdate_] := Block[{year, nextBirthday}, (* get the current year *) year = Today["Year"]; (* replace the birthday year with the year of the next birthday *) nextBirthday = DateList[birthdate]; nextBirthday[[1]] = year; If[DateDifference[Today, nextBirthday] < 0, nextBirthday[[1]] = year + 1]; (* return the number of days to the next birthday *) DateDifference[Today, nextBirthday] ]

Make a web page using those functions. Use Style and Row to format the output nicely:

CloudDeploy[FormFunction[ FormObject[{"date" -> <|"Interpreter" -> "Date", "Label" -> "birth date:"|>}], Style[Row[{" You are ", Style[DaysOld[#date], 18], " days old and have ", Style[DaysToNextBirthday[#date], 18], " days until your next birthday."}], FontFamily -> "Times"] &, "HTML"], Permissions -> "Public"]

Click the URL in the previous output to visit the page.