It is possible in asp.net 2 that c# an vb.net classes can be used in same project
All class files are contained in app_Code folder which is compiled into single assembly.
It is possible that classes placed in same folder causes error. So make different folders in app_data such as “vbclasses” and “c#classes”
App_Code
vbclasses
c#classes
now places vb and c# classes in their respective folders as
App_Code
vbclasses
someClass.vb
c#classes
otherClass.cs
now we have to add some lines in web.config under the compilation key
<compilation>
<codeSubDirectories>
<add directoryName=”vbclasses”></add>
<add directoryName=”c#classes”></add>
</codeSubDirectories>
</compilation>
now asp.net compile the code in single assembly and we can use the implementation of code placed in vb or c# class in our application without specifying their extensions