How can I use generic here

Question

I am trying to use generic for the first time and trying to typecast my result returned from database to programmer defined data type. How can I do this.

dsb.ExecuteQuery("DELETE FROM CurrencyMaster WHERE CurrencyMasterId=" + returnValueFromGrid<int>(getSelectedRowIndex(), "CurrencyMasterId")); private T returnValueFromGrid<T>(int RowNo, string ColName) { return Convert.ChangeType(dgvCurrencyMaster.Rows[RowNo].Cells[ColName].Value, T); }

Don't mix backquotes and four-space indent. Only one of those is required to mark up code. — Marcelo Cantos
– Marcelo Cantos, Commented Apr 23, 2010 at 9:30

Jon Skeet · Accepted Answer · 2010-04-23 09:30:15Z

3

You're trying to use T as a value - you want the type T represents, and then you'll need a cast as well:

object value = dgvCurrencyMaster.Rows[RowNo].Cells[ColName].Value; return (T) Convert.ChangeType(value, typeof(T));

answered Apr 23, 2010 at 9:30

Jon Skeet

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4 Comments

Shantanu Gupta Over a year ago

@Jon: Thx it worked, I did't thought that there is typeof also. I was using getType. I need 1 more favour here plz. Where can i use generic in my real time applications. Is it a proper use of generic or generic is used in some different situations ?

Jon Skeet Over a year ago

@Shantanu: I'm not really sure what you're asking. Generics are indeed used in all kinds of different situations. Collections are the most common use, but far from the only one.

Shantanu Gupta Over a year ago

I am trying to get some data from database base which have different different data types say string, int, binary etc which programmer will be specifying after looking what value he/she need to display then accordingly he will be typecasting and using. Is it a one of the use or should it be done from application user rather than programmer

Jon Skeet Over a year ago

@Shantanu: In this case I don't think there's likely to be much benefit in having a generic method over just casting - you'll still need to specify the type, after all.

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