Simple update check function

• Download source files - 2.5 Kb

Introduction

Almost all programs that are available today have a feature that checks for software updates using the internet. This is a convenient way for both the user and the developer: You don't have to contact all the users (if you know them...) when a new version is available. And the user can be sure to always have the newest version.

In this article I'd like to focus on small programs (e.g. only 1 executable and no nescessary installation program) and developers who have just a simple web space without the possibility to use scripts (only static web pages). Also this code only shows a web page and does not automatically download or install files.

The basic thing we have to do is very simple: Connect to a web site, ask for the newest version, compare it to the current version, and in case there is an update ask the user to download it. You - as the developer - have to use correct version information in your code and update the internet file whenever an update is available.

Program version

What this class does

Using the code, allow auto-updates

void CMyApp::OnAppCheckupdate()
{
  CUpdateCheck checkUpdate;
  checkUpdate.Check(IDS_UPDATE);
}

In case you want to check automatically for updates each time the user start your application put the lines above in the InitInstance function. Or write the last date you checked for updates to the registry and only check once each week. ....

[2]: Add a few strings to the string table:

[3]: Put a file on your webspace (located as referred in IDS_UPDATE) which has the following syntax:

Major Version|Minor Version|URL for Update page

3|4|http://www.mydomain.com/updateinfo.html

Limitations

• The file on your web site has to be less than 512 characters
• Only the two leftmost parts of the version info are used. The lower two numbers are normally used as a "Build number" and have no effect on this class
• No automatic download is offered, the user has to download the files from your site and copy/install them

History

01.11.2003: Initial release

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)