From the June 2010 Issue of Prestwood eMag

Paradox OPAL: Language Details: Using IsFile() Example By Mike Prestwood

Posted 16 years ago on 6/3/2008 Take Away: ObjectPAL IsFile example demonstrates how to check if a file exists. KB101146

Suppose that you wish to find out whether a file exists. In this example, you use the fact that isFile() returns a Logical to determine wether a file exists.

Create a form and add a button to it. Label the button Using a Logical.

Add lines 3-8 to the pushButton event of the Using a Logical button. Line 4 declares l as a Logical variable. isFile() returns True if the file exists and False if it doesn't. In line 7, l is given this return value from isFile(). Line 8 displays the result. Note that you passed view() a title to display.

 1: ;DATATYPE :: btnLogical :: ushbutton
 2: method ushbutton(var eventInfo Event)
 3: var
 4:   lFileExist   Logical
 5: endVar
 6:
 7: lFileExist = isFile("C:\\AUTOEXEC.BAT")   ;Note the double "\"
 8: lFileExist.view("Does file exist?")
 9: endMethod

Check the syntax, save the form as ISFILE.FSL, and run it. Click the button. The Logical viewer will display True or False, depending on whether the file exists.

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KB Post Contributed By Mike Prestwood:

Mike Prestwood is a drummer, an author, and creator of the PrestwoodBoards online community. He is the President & CEO of Prestwood IT Solutions. Prestwood IT provides Coding, Website, and Computer Tech services. Mike has authored 6 computer books and over 1,200 articles. As a drummer, he maintains play-drums.com and has authored 3 drum books. If you have a project you wish to discuss with Mike, you can send him a private message through his PrestwoodBoards home page or call him 9AM to 4PM PST at 916-726-5675 x205. Visit Profile