.NET Tip: Type Casting and Comparison Using "as" and "is" Boston MA

Use some of the language's lesser known features for safe type casting and comparison.

Local Companies

Eze Castle Integration
(617) 217-3000
1 Federal Street, 9th Flr.
Boston, MA
Cogent Communications
(617) 482-5546
1 Summer Street, Ste. 450
Boston, MA
WordStream Internet Marketing
617-457-7870
133 Federal St.
Boston, MA
Applied Technologies, Inc.
(617) 742-2525
One Center Plaza, Ste. 240
Boston, MA
Thomas Reuters
(617) 856-2000
22 Thomson Place
Boston, MA
Starr Center @ The Schepens Eye Research Instittute
(617) 912-0100
185 Cambridge Street, 2nd Floor
Boston, MA
VIPER consulting_inc
(617)6860170
660 Massachusetts Avenue, Suite 6
Boston, MA
JCALPRO
(617) 954-2345
415 Summer Street
Boston, MA
INX Inc.
(617) 728-4440
2 Oliver Street, 10th Floor
Boston, MA
Brattle Consulting Group, Inc.
(617) 229-7210
8 Faneuil Hall Marketplace
Boston, MA

provided by: 
Originally published at Internet.com


You are probably used to using C-style casts. Look at an example starting with C-style casts and see how using "as" and "is" can help your code. A common situation I run into is working with controls in an ASP.NET DataGrid. Suppose I need to work with the DataGridItem that is the parent of one of the controls in the grid. Using C-style type casting, I would do something like this: // C-style try { DataGridItem item = (DataGridItem)mycontrol.Parent; if (item.GetType().ToString() == "DataGridItem") { // Do something interesting here } } catch (InvalidCastException ex) { }

Although this method works, there is a much cleaner way. First, I'll address the type cast and exception handling using "as". With "as", there is no need to check for exceptions Because it will either return the object as the requested type or it will return null. You then can check the value against null to see whether the type conversion was successful. // Using As DataGridItem item = mycontrol.Parent as DataGridItem; if (item != null) { // Do something interesting here }

This code is much more concise and explicit than when using C-style type casting. Adding the use of "is" in the comparison makes this code more readable and is slightly more efficient than the comparison to null. The end result looks like this: // Using As and Is DataGridItem item = mycontrol.Parent as DataGridItem; if (item is DataGridItem) { // Do something interesting here }

Compare this with the original version using C-style type casting. I think that you will agree the version using "as" and "is" is easier to understand and maintain because there is no need to worry about invalid cast exceptions.

About the Author

Jay Miller is a Software Engineer with Electronic Tracking Systems, a company dedicated to robbery prevention, apprehension, and recovery based in Carrollton, Texas. Jay has been working with .NET since the release of the first beta and is co-author of Learn Microsoft Visual Basic.Net In a Weekend. Jay can be reached via email at jmiller@sm-ets.com.

Author: Jay Miller

Read article at Internet.com site

Featured Local Company

Eze Castle Integration

(617) 217-3000
1 Federal Street, 9th Flr.
Boston, MA

Related Local Events
Software Development Best Practices 2009
Dates: 9/21/2009 - 9/24/2009
Location: Hynes Convention Center
Boston, MA
View Details

EMBEDDED SYSTEMS CONFERENCE - BOSTON 2009
Dates: 9/21/2009 - 9/24/2009
Location: Hynes Convention Center
Boston, MA
View Details

September Networking Breakfast
Dates: 9/15/2009 - 9/15/2009
Location: Holiday Inn Boston - Somerville
Somerville, MA
View Details

September Networking Breakfast
Dates: 9/15/2009 - 9/15/2009
Location: Holiday Inn Boston - Somerville
Somerville, MA
View Details

LINUXWORLD SUMMIT 2009
Dates: 9/1/2009 - 9/1/2009
Location: IDG World Expo
Framingham, MA
View Details