One of the way to enumerate the Environment Variables is by accessing _environ global variable. The GetEnvironmentStrings function provides another way by returning a pointer to the environment block of the calling process. It can also be done using WMI Win32_Environment Class.

The number of jobs in print queue can be retrieved by simplified version of Enumerating jobs in print queue

Enumerating jobs in a print queue can be done with

• WMI Win32_PrintJob class
• Windows API EnumJobs function.

All jobs from a print queue can be deleted with

• WMI Win32_Printer class and CancelAllJobs method
• Windows API SetPrinter function.

The WMI Win32_Process class

represents a process on an operating system.

Relevant MSDN links:

• Windows System Services - Service Functions
• Windows Shell - IsServiceRunning Method
• Windows Shell - ServiceStart Method
• Windows Shell - ServiceStop Method

Sometimes it's necessary to change Windows default printer from within VFP application. It can be done with Windows API, WSH or WMI.