Beginner to Amiga coding.

[Thorham]

Here's a cleaned up version of your test program. The example program you based your program on uses global variables (this is often not good), and it opens libraries needlessly (for system libraries it's not needed). There's also no need for declaring prototypes for programs like this. Just have functions appear in the order in which they are used, with the main function appearing last.

#include <stdio.h>

#include <exec/types.h>
#include <graphics/gfx.h>
#include <intuition/intuition.h>
#include <dos/dos.h>

/* Prototypes for system functions. */

#include <proto/exec.h>
#include <proto/graphics.h>
#include <proto/intuition.h>
#include <proto/dos.h>

void drawGfx(struct Window *win)
{
    int c;

    for (c = 0; c < 201; c += 5)
    {
        Move(win->RPort, 0, c);
        Draw(win->RPort, 200 - c, 0);
        Draw(win->RPort, 200, 200 - c);
        Draw(win->RPort, c, 200);
        Draw(win->RPort, 0, c);
    }
}

int main(void)
{
    struct Window *myWindow;

    /* Open wiwndow. */
    myWindow = OpenWindowTags(NULL,
        WA_Left, 20,
        WA_Top, 20,
        WA_Width, 210,
        WA_Height, 214,
        WA_Title, (ULONG)"Troys Draw Demo Win",
        WA_DepthGadget, TRUE,
        WA_CloseGadget, TRUE,
        WA_SizeGadget, FALSE,
        WA_DragBar, TRUE,
        WA_GimmeZeroZero, TRUE,
        WA_IDCMP, IDCMP_CLOSEWINDOW | IDCMP_MOUSEBUTTONS | IDCMP_MOUSEMOVE,
        TAG_END);

    /* Print error message and exit if window couldn't be opened. */
    if (myWindow == NULL)
    {
        printf("Couldn't open window.\n");
        return 0;
    }

    drawGfx(myWindow);

    Delay(500);

    CloseWindow(myWindow);

    return 0;
}

drawtest.c

Originally Posted by Zetr0

I used to use Dice / Lattice C as well as SAS - hmmm

SASC6.58 will give you Error 218: declaration in statement block if you try that.

[alkis]

Originally Posted by Zetr0

hmmm I will test this later as I might be wrong but I do remember writing out the following syntax quite often.

for( int index =0; blah ; blah )

and if memory serves I would write this loop out a lot, when chunking data from FAST to CHIP

for( register int index =0; blah ; blah )

I used to use Dice / Lattice C as well as SAS - hmmm

Tested it. Doesn't work.

#include <stdio.h>

int main(int argc, char **argv)
{
  for(int i=0; i<10; ++i)
        printf("%d\n");
  return 0;
}
SAS/C Amiga Compiler 6.58
Copyright (c) 1988-1995 SAS Institute Inc.

====================
  for(int i=0; i<10; ++i)
foo.c 5 Error 218: declaration found in statement block

[alkis]

Ok, one design issue I'd change. (I'll use Thorham's cleaned up version as reference)

This line on your OpenWindow

WA_IDCMP, IDCMP_CLOSEWINDOW | IDCMP_MOUSEBUTTONS | IDCMP_MOUSEMOVE,

tells Intuition what messages you are interested for this window to receive.

You can delete mousebuttons and mousemove and make it

WA_IDCMP, IDCMP_CLOSEWINDOW,

So, only when user clicks the close window button we'll get a message.
Then you can replace the Delay line with

Wait(1 << myWindow->UserPort->mp_SigBit);

and now the program terminates whenever user closes the window.

[Zetr0]

@davideo

Originally Posted by davideo

@Zetr0

I found some of your coding at one point. I believe it was on Aminet but can't seem to locate it now!!

LOL, not sure I remember uploading any 'C' code to Aminet, but now you have me excited too =)

@alkis

Thanks for testing, I don't remember having a later version of SAS, possible SAS 2 or 3 at the most on the Amiga, I did use Dice/Lattice a lot before SAS - and then Storm C 3.0 about a year afterwards.

Its entirely possible this is a habbit I have picked up programming on PC's

[TroyWilkins]

Thank you everyone for the great input, I'm learning and I really honestly appreciate everyones suggestions and help.

It seems to me that there are some fairly large differences between the sort of BASIC I'm used to and C - which is to be expected, but which does make the learning curve just that bit steeper. And no, I'm not talking about line numbers or (dare I mention it hehe) goto, I'm talking about reserved words and handling of variables.

I mean, BASIC is pretty darn easy, A (numeric variable), B$ (string variable), and C(10) one dimensional array of numeric variables. It feels like C is a lot more complex here, but also offers a lot more flexibility once you get your head around it. And from what I've read looking around on the internet, it's not just me, this is one of the stumbling blocks for most people new to C, particularly when it comes to pointers and so forth.

With reserved words, it seems to me that there are less reserved words than I am used to in basic, but that words can be reserved as functions rather easily, and often are in what you #include, so it can easily and quickly become virtually unlimited, depending on the includes?

I'll certainly be coming back to this little exercise, for one I want to try to work out why I can't get PolyDraw to work for this, and for another learning exercise, I want to make the window re-sizable and have it redraw to suit when it is resized. Obviously this will mean getting rid of the fixed numbers and replacing them with variables obtained from the size of the window, as well as listening for a resize event - in the correct order of course.

Also, I can use this for learning about menus - perhaps add a menu for line drawing style and colour, as well as a menu option to quit.

[TroyWilkins]

This looks like a very handy site, I wish I'd found it sooner: http://www.pjhutchison.org/tutorial/amiga_c.html

[Thorham]

Originally Posted by TroyWilkins

This looks like a very handy site, I wish I'd found it sooner: http://www.pjhutchison.org/tutorial/amiga_c.html

Don't forget general C sites. SASC6.58 is C89. Anything dealing with that will work (large parts of current C standard).

[Samurai_Crow]

The Amiga operating system uses many pointer-based operations. If you learn them well, it will help later on.

C, however, is a really unforgiving language. IMO it should not be a first language and is unsuitable for beginners. My suggestion is to learn an easier language first and then come back to it. What is your goal?

[TroyWilkins]

Originally Posted by Samurai_Crow

The Amiga operating system uses many pointer-based operations. If you learn them well, it will help later on.

C, however, is a really unforgiving language. IMO it should not be a first language and is unsuitable for beginners. My suggestion is to learn an easier language first and then come back to it. What is your goal?

I am somewhat literate in BASIC, although more literate in ancient dialects such as Atari BASIC on the 8-bits, and Commodore BASIC V2. I have meddled with Pascal (a long time ago), Java, and more modern BASIC versions, although I wouldn't consider myself anything more than a beginner using any of them.

My goal is to learn and write system legal code that works with, and takes advantage of, intuition, mainly as a learning tool to help me understand the software side of the Amiga better. If that means I can then, later on, write my own programs to use and maybe even release to Aminet for others to use if they so desire, even better, but for now, it's mainly a learning tool.

[Thorham]

Originally Posted by TroyWilkins

I am somewhat literate in BASIC, although more literate in ancient dialects such as Atari BASIC on the 8-bits, and Commodore BASIC V2. I have meddled with Pascal (a long time ago), Java, and more modern BASIC versions, although I wouldn't consider myself anything more than a beginner using any of them.

Then stick with C. The knowledge gained will also be useful on the peecee, because C is C. There's no such thing as Amiga C or peecee C. Except for newer versions having more features than older versions, it's all the same (unless you go way back to the 80s or before). Of course all the system calls will be different, but that's pretty obvious.

[alkis]

I agree with Thorham.

If you want to learn something that you can use everywhere, stick with C. If you choose to make your objective to learn C, then I'd suggest to put amiga specific programming in the background and focus on the language itself. Find (google) the "the c programming language by kernighan and ritchie". Go through it. Write the included programs on your amiga. Compile them. Run. Make yourself familiar.

Writting a 'wc' (word count) program feels good for a newbie! At least it did for me!

Whatever you do, just have fun!

[Samurai_Crow]

If, on the other hand, you want to make Amiga coding your focus then pick an Amiga-specific language like AmigaE or Blitz BASIC 2.1. That way you'll know it will work on a 25 year old computer like yours without a new compiler.

[Selur]

On miggy I would chose Amos/Blitz and after that finally assembler, never C.

[Thorham]

Originally Posted by Selur

never C

Why? C is great for utility software.

[TroyWilkins]

Sorry for digging up an old thread, but I'm coming back to this after a few years, and now am trying a different approach, using my Windows 10 machine to write and cross-compile using VCC, using the VBCC tool chain as found here on EAB: http://eab.abime.net/showthread.php?t=83113

I'm probably doing something stupid, but when I attempt to compile the cleaned up version by Thorham it doesn't compile and gives the following output:

D:\Amiga>vc -o Test1 Test1.c
\Users\thema\AppData\Local\Temp\vbcc068c.o: In "_drawGfx":
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x16): Reference to undefined symbol _GfxBase.
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x2e): Reference to undefined symbol _GfxBase.
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x4c): Reference to undefined symbol _GfxBase.
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x62): Reference to undefined symbol _GfxBase.
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x74): Reference to undefined symbol _GfxBase.
\Users\thema\AppData\Local\Temp\vbcc068c.o: In "_main":
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x106): Reference to undefined symbol _IntuitionBase.
\Users\thema\AppData\Local\Temp\vbcc068c.o: In "l14":
Error 21: \Users\thema\AppData\Local\Temp\vbcc068c.o (CODE+0x14a): Reference to undefined symbol _IntuitionBase.
vlink -bamigahunk -x -Bstatic -Cvbcc -nostdlib -mrel "C:\Users\thema\OneDrive\Desktop\vbcc\targets\m68k-amigaos\lib\startup.o" "C:\Users\thema\AppData\Local\Temp\vbcc068c.o"   -s -Rshort -L"C:\Users\thema\OneDrive\Desktop\vbcc\targets\m68k-amigaos\lib" -L"C:\Users\thema\OneDrive\Desktop\vbcc\ndk39\include\linker_libs" -lvc -o Test1 failed

D:\Amiga>

[Samurai_Crow]

Those are linker errors. Try linking Amiga.lib.

[Ami]

Add -lauto option to vlink.