When to convert datatypes in asp.net?

Hey..

I am realy confused i dont know when too data convert in asp.net!

When iam talking about comverting, i mean like this:  Int32.Parse..tostring()..and so on!

should i convert when a read text fra a textbox,dropdownlist, too a specifc datatype ?

I havde ssen , that when you read data from a database, you convert data  in...like (string)reader("datafiel").tostring...and so on..

I hope you guys can understand my problem....

 

thanks!
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