Regular expression for date....

Question

i have a textbox
one calender control
on selecting date from calender control date goes in format "Aug 19, 2011" ("MMM dd, yyyy") into textbox
i want the regular expression that if user input date directly into textbox than regular expression is in format Aug 19, 2011 ("MMM dd, yyyy") or not.

actualy i wanted that there should be no option for manual entry into the textbox, but when i use readonly or enabled property and try to insert value into database then null value is retrieved from textbox

nyway, the regular expression will do...
can nyone help

Vulpes · Answer

Here's a better regular expression which ensures that the date is between 01 and 31: string regExp = @^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) ([0-2][1-9]|3(0|1)) \d{4}$; However it's tough to come up with one which checks the maximum number of days in a given month (i.e. 28 29 30 or 31) and checks for leap years too. Frankly it's easier to use the DateTime.TryParse() method rather than a regular expression for this.

Vulpes · Answer

It's just dawned on me that it's a web application rather than a windows forms application but I'm still mystified why setting the TextBox to ReadOnly doesn't work for you. As long as ViewState is enabled for the page then the Text property will be persisted between postbacks and can't therefore be null. In fact I've just tried it myself and the Text property of a readonly Textbox saved to disk just fine. My suspicion therefore is that the problem is something to do with how you're saving it to the database rather than the readonly status of the TextBox itself.

nishant ranjan · Answer

actually i want that i should not be allowed to enter date in textbox only through calender control we can enter the date and not by directly typing in the textbox.... then i hv to store that textbox data into database

Vulpes · Answer

I'm puzzled by what you say as you should still be able to retrieve the Text property of a TextBox programatically even if it is readonly or disabled. What do you get when you do: MessageBox.Show(textBox1.Text);

nishant ranjan · Answer

thanks it working can you let me know how can i retrieve data from textbox.text when textbox property is set to either readonly or enabled=false... on either case i get null value...

Vulpes · Answer

Try: string date = Aug 19 2011; string regExp = @^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \d{2} \d{4}$; bool isMatch = Regex.IsMatch(date regExp); // True