The LA Fox Developer Newsletter

August 1999

Use Version Information to

Keep Track of Executables

A user is phoning you for help. Are you sure you are talking

about the sameversion?

If you have more than one build of your application in the field,

you need a way of knowing which one a given person is using.

Visual FoxPro (5.0 and above) can help with this, by branding

the executable with a version number and related information.

To see how this works, open the application in Project Manager,

then click on Build, then Versions. You will see a dialog in

which you can enter a version number, product name, company

name, file description, and several similar items (see Figure 1).

The version number consists of three parts: major, minor and

revision.

Figure 1: Use this dialog to specify version information.

When you build the application, this information gets stored

inside the EXE file. From there, it can be accessed both

programmatically and by the user.

More interestingly, if you check the Auto Increment option within

the dialog, the version number will be incremented with each

build, thus ensuring that it is unique within your application. (In

fact, it is the revision number which is incremented; if you want

to change the major or minor component, you must do so

manually.)

Over to the user

So how do you find out which version a given user is using? One

option would be to ask them to look at the file properties of the

application’s EXE file. To do that, they must locate the file in

Windows Explorer or a folder window, right-click on it, select

Properties, then click on the Version tab. All the information that

you entered in the Project Manager’s Versions dialog will be

displayed (see Figure 2).

Figure 2: The version information can be accessed from the

Windows shell.

A slicker approach would be for the application itself to retrieve

this information, and to display it somewhere where the user

can easily get at it - such as in the About box on the Help

menu.

To retrieve the version information from within your program, call

the AGETFILEVERSIONO function. Pass it two parameters: the

name of an array to hold the information, and the name of the

executable file. As with most of the “A” functions, if the array

does not already exist, the function will create it. If it does exist,

it will be re-sized as necessaly . . .

For example, this command retrieves version information from a

file called MYAPP.EXE, and stores it in array aVer:

InReply AGETFILEVERSION(aVer,”MYAPP.EXE”)

By the way, the function returns zero if the file does not contain

Windows versioning information.

The three-part version number can be found in the fourth ele-

ment of the array (check the VFP help for the contents of the

other elements). It is returned in decimal format, with periods

between the components. So if you entered 1, 2 and 3 in the

major, minor and revision fields respectively, the number would

be returned as 1.2.3. Note that the three components are

strictly numeric: you cannot specify 1 .2a, nor could you make a

distinction between 1.2 and 1.02.

GETFILEVERSION() was introduced as a native command in

VFP 6.0. In earlier releases, the equivalent functionality was

provided within Foxtools.

Copyright Mike Lewis Consultants Ltd. 1999.

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