Comparing two times that are shown on form as dropdowns for hours and minutes

Question

I have been working on a .NET/C# form that contains two time fields that are built out of dropdowns. Time A is made up of two dropdowns for Hours and Minutes and Time B is made up of two drop downs for hours and minutes too. I need to compare the two in order to ensure that Time A is always greater than B.

I could just use a CompareValidator to check the hours, that works BUT doesn't take into account the minutes. So lets assume the following scenarios:

A = 11:00 B = 12:15 is fine my validation accepts this as it should do A = 11:15 B = 11:00 is accepted because the hours are equal but otherwise shouldn't pass as the minutes aren't validated

How would you ensure B is always equal to or greater than A where dropdowns are used? I would if I could change this but not permitted to do so.

Answer 1

I believe the best way is to have a method which encapsulates the comparison and internally is creating two DateTime values, a and b, and comparing them.

Such method will initialize a and b with the values of the UI.

Answer 2

Why not add a CustomValidator and write a little javascript function to compare the dates?