Visual Basic Concepts

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Project File Formats

Microsoft Visual Basic utilizes and creates a number of files at both design and run time. Which files will be required by your project or application depends upon its scope and functionality.

Project File Extensions

Visual Basic produces a number of files when you create and compile a project. These can be categorized as follows: design-time, miscellaneous development, and run-time.

Design time files are the building blocks of your project: basic modules (.bas) and form modules (.frm), for example.

Miscellaneous files are produced by various processes and functions of the Visual Basic development environment: Package and Deployment Wizard dependency files (.dep), for example.

Design-time and Miscellaneous Files

The following table lists all the design-time and miscellaneous other files that may be produced when you develop an application:

Extension Description
.bas Basic module
.cls Class module
.ctl User Control file
.ctx User Control binary file
.dca Active Designer cache
.ddf Package and Deployment Wizard CAB information file
.dep Package and Deployment Wizard dependency file
.dob ActiveX document form file
.dox ActiveX document binary form file
.dsr Active Designer file
.dsx Active Designer binary file
.dws Deployment wizard script file
.frm Form file
.frx Binary form file
.log Log file for load errors
.oca Control TypeLib cache file
.pag Property page file
.pgx Binary property page file
.res Resource file
.tlb Remote Automation TypeLib file
.vbg Visual Basic group project file
.vbl Control licensing file
.vbp Visual Basic project file
.vbr Remote Automation registration file
.vbw Visual Basic project workspace file
.vbz Wizard launch file
.wct WebClass HTML template

Run-Time Files

When you compile your application, all the necessary design-time files are included in the run-time executable files. Run-time files are listed in the following table:

Extension Description
.dll In-process ActiveX component
.exe Executable file or ActiveX component
.ocx ActiveX control
.vbd ActiveX document state file
.wct WebClass HTML template