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Archive Magazine 1996
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volume_6
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issue_06
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cfrombasic
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ReadMe
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1993-01-23
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C Example by Thomas Down
============================
This is an example of how to write a (very) simple RISC-OS WIMP
application in C. To use it, simply double click on its icon. Notice that
there is an icon bar menu with info and quit options. When you click on its
icon, a small dialog box opens containing three icons. Try clicking and
typing to see what they do.
To find out how it works, load the c.cexample file into a text editor.
Most commands are explained by comments in the text file, but remember the
following
1. /* ... */ is equivalent to Basic's REM ...
2. C uses a form of block structuring. {and } are used to group
instructions together. For example, the IF command can be used with one
conditional instruction:
if(var==1)
instruction 1
or several:
if (var==1) {1 ;
...
instruction n;
}
3. C uses semicolons (;) as line terminators after most instructions. The
exceptions are instructions which are followed by one or more other
instructions to make a statement e.g. for(), if(), while().
4. In C, the equality condition is '==' instead of Basic's '='. '=' is
still used for assignment.
-----------------------------------------------------------------------------
IF YOU WANT TO RECOMPILE THE PROGRAM
ANSI C v4
I do not recommend using ANSI C from floppies unless absolutely necessary
Open the 'c' and '!C Example' directory viewers. Now load !CC. To compile
and link, drag the cexample file from the 'c' directory to the !CC icon.
The default options are generally correct so simply click Run. A text
window will open showing progress. Ignore the warning from 'link' about a
memory shortage. When compilation is complete, a save box will appear.
Delete the default name and type in '!RunImage' then drag the icon to the
!C Example directory. This sounds a bit complicated, but very quickly
becomes intuitive.
BEEBUG C (v 1.50)
If you are using floppy discs, copy the cexample directory onto your work
disc
1. Load the editor
2. Check the options are correct. You will need to link with:
Window library
Event library
Menu library
Dialog box library
Icon library
Utilities library
(if in doubt about these, use Complete WIMP)
OS library
Sprite library
Shared C Library
This is NOT the default configuration, so you MUST change it unless you
have already reconfigured the package.
3. Load c.cexample into the editor
4. Click on the Compile menu option
5. If the compilation is successful, click on the Link menu option
6. In the directory ABOVE the 'c' directory, there should now be an APP
file called cexample. Rename this !RunImage
7. Copy the new !RunImage into the !C Example application directory