If you are at this page, we conviniently assume that you have downloaded the code, looked through it, and maybe even tried it out. We recommend it. If you have problems running it, send a email to us at lccorp1997@hotmail.com.
Your Lesson Starts Proper
The first thing you must have noticed about our program is that it must be in "c:\ultima8\" in order to work. Why is this so? Well, QBasic programs operate with a default directory in mind. This directory is by default the one in which the Qbasic.exe file is located in. If you use Open in your program without stating a direct path, QBasic will assume that the file is in the working directory. In our case, Ultima8 is our default directory. The default directory can be changed using the Chdir command. So, an alternative to using a direct path Chdir and forcing your user to put the program in a specified directory is to use variable subsitution.
SCREEN 12: COLOR 15: CLS OPEN "setting.ini" FOR INPUT AS #1 INPUT #1, whether$: IF whether$ = "" THEN GOTO question GOTO program question: INPUT "Enter the directory in which the program is located: "; locatedir$ CHDIR locatedir$ PRINT "" INPUT "Do you wish to save this setting? (Y/N)"; savesetting$ IF UCASE(savesetting$) = "Y" THEN GOTO filesave GOTO program program: ' Program Code SYSTEM filesave: OPEN "setting.ini" FOR OUTPUT AS #1: PRINT savesetting$, #1: CLOSE #1 PRINT "" PRINT "Your settings have been saved!" GOTO program
- A program must have a Chdir to specify the default directory.
The next thing about a program is that you should make a setup program that will check whether the user has unzipped and setup your program successfully. This will help prevent complications later. A good way to do this is to make it a seperate program and use the Chain command to link them. Remember, QBasic has a built-in limit to how large your program can be. Keep that always in mind and use Chain to make chained programs, both to combat this and for easy file management and administrative purposes.
Notice that there are a few .bas files in the .zip and not just one.
- Try to use chained files whenever possible. Also create setup programs.
Finally, we share with you a little tip on how to check whether files are there. Use the On Error command to specify a line label that will lead an error message stating the file is not there. Define the On Error just before your checking code. Then use Open to open each file you want to check and then Close it. If a file is not there the program will jump to the On Error label.
For example:
On Error GOTO nofile OPEN "c:\autoexec.bat" FOR INPUT AS #1 CLOSE #1 PRINT "Your file is there!" SYSTEM nofile: PRINT "We couldn't find your autoexec.bat file!" SYSTEM
- Check to make sure all files are there.
And finally, always specify an On Error label just in case something goes wrong.
On Error GOTO internalerror PRINT "There was an abnormal internal error during program execution." PRINT "Program will Terminate." SYSTEM
- Don't forget to include safety valves in your programs!
Well, that's all for your basics. Click below to go on!
Email: lccorp1997@hotmail.com
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This Webpage created for Thinkquest 1998.