comparison between two values

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I have a variable; i.e. oDateTime with the type of DateTime & I extracted a time from it as follows:

C#

string.Format("{0:t}", oDateTime);

Now my output is 4:00AM

My dropdownlist controls having the values like 01,02.....12 for Hours and 01,02...59 for Minutes & AM,PM for FormatDropdown control.

Now here on button click event it will retrieve the values & will show those values in controls as selected value as follows:

C#

ddlTFHrs.SelectedValue = String.Format("{0:hh}", oDateTime);

ddlTFMin.SelectedValue = String.Format("{0:mm}", oDateTime);

ddlTFAMPM.SelectedValue = String.Format("{0:tt}", oDateTime);

Here I am getting an error when I try to compare 04 with 4.

Can I format the time in string format as 04 or else is there any alternate way to compare these two values?

Thanks

Posted 11-Apr-12 5:51am

SIVA RAMAMOORTHY

Updated 11-Apr-12 5:57am

R. Giskard Reventlov

v2

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sjelen 11-Apr-12 12:52pm

String.Format("{0:hh}", oDateTime);
should format like 04.
Can you show how do you bind or populate dropdownlists?
Maybe text in dropdownlist items are '01', '02',... and values are '1', '2'?

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OriginalGriff · Accepted Answer · 2012-04-11T06:01:00

Solution 1

Don't convert it to a string - that is always a pain.
Instead, use http://msdn.microsoft.com/en-us/library/system.datetime.timeofday.aspx[^]

C#

TimeSpan timeOnly = DateTime.Now.TimeOfDay;

You can then compare this with your time of day directly.

Posted 11-Apr-12 6:01am

OriginalGriff

Comments

Sergey Alexandrovich Kryukov 11-Apr-12 12:59pm

My 5 just for the first sentence. Trying to work with string representation of data instead of data is one curse of the beginners.
--SA

sjelen 11-Apr-12 13:18pm

True, but I think this is not the issue here. DropDownList.SelectedValue is a string, so he must convert whatever data type he uses to string in order to set selected item.

OriginalGriff 11-Apr-12 13:58pm

No, you have the wrong idea entirely!
Never convert anything to a string to compare it: convert strings to math-friendly values, then compare them.
General rule of working with data: Convert from string as early as possible, Convert to string as late as possible.
And never do math on strings! :laugh:

sjelen 12-Apr-12 10:10am

It's possible I got him wrong, but he did left out the code used for comparison. So I assumed the problem arose when he set SelectedValue and DropDownList must (internally) use string comparison against it's list of values to find selected item...
I completely agree with conversion rules, you already got mu +5 for that.