developing a simple Text editor in C

Hi all,

I am pretty new to c programming. At present, I have a taken up a project of developing a Simple Text Editor using C.

But I couldnt visualize, how a text editor could be programmed in C.

In a text editor program, user should be able to edit the text in the screen directly. User should be able to use ARROW KEYS / BACKSPACE / DELETE key etc.

I would be of a great help if someone could help me with some basic idea/algorithm required for developing the text editor like

1. How to accept keys from user.
2. How to display the characters accordingly.

Thanks
rssrik

If you're new to C programming, I would not attempt it, yet.

I would not recommend one write a book of poetry or write a novel, before gaining a strong command of English, or some other language that they would be writing in. Similarly, learn C and get very good at it, before trying something large. Something like a text editor in C is more advanced than you might think it to be.

Quote:

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Originally Posted by rssrik

I would be of a great help if someone could help me with some basic idea/algorithm required for developing the text editor like

1. How to accept keys from user.
2. How to display the characters accordingly.

---

Those are trivial questions that require looking at documentation to find the answer. The more interesting question is, what data structure are you going to use to represent the opened text file in relation to its position on screen and the position of the cursor?

Thanks for reminding me that I am a beginner.

But I am not a absolete "Hello worlder". I think I can handle it. Only problem is that I dont know where to start !!!

I will appeciate If you could give me some basic ideas. (i'm not requesting for code)

Thanks again,
rssrik

Looks like you have identified the problematic parts of writing a text editor.
Trouble is that standard c doesnt support any of this functions. So you will have to use external libraries ( like ncurses ) or use OS functions.
Kurt

Here is a link which may be of use - Lnote. It is a text editor written in gtk+. You could download the source and have a look at it, it may not be of any use to you though as it may require a fair bit knowledge to understand. In any case, here is a gtk+ 2.0 tutorial to get you started.

You can write a very simple text editor if you're using Dev-C++ under Windows with getche() from the non-standard <conio.h>; getch() might work too with new versions of Dev-C++. What's the difference? http://www.daniweb.com/forums/thread37195.html

If you want to have a cursor-moving function you can use gotoxy(), also in <conio.h>. An implementation of it for Windows compilers can be found here: http://forums.devshed.com/c-programm...ct-149226.html

That's if you don't want to use ncurses or another library. We don't really know your level of programming ability so I don't know what to recommend.

Thanks Zuk & DwkS,

I read the NCURSES LIB and it seems to hav most of the tools for developing an editor.
I think it is portable too !

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gcc (rssrik).c libncurses.a

You know that you should link with libraries with -lncurses (for libncurses.a)?

Yes, ncurses is definitely a better way than using getch() etc, but it's a bit harder.

Anyway, good luck.

libncurses.a is the NCURSES library to get linked with the code !

I am using "Linked List" to back the representation in screen. The default screen has 25 lines.
I need to know, How many lines should I BUFFER in memory to represent the screen ?

1. Suppose If I BUFFER only the 25 lines to be displayed in screen, then for every "PAGE_UP/PAGEDOWN/UPARROW/DOWNARROW" operation, I will have to read the required lines from the file and display it.

I feel these instructions would take few secs.

2. If I BUFFER 5-6 pages in memory itself, then i FEEL that precious memory is wasted.

Could someone justify, which is best method.

Thanks
gcc -lncurses rssrik.c

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Those who succeed, will wake up and work for it !!!
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> then i FEEL that precious memory is wasted.
"precious"?
How many MB or GB of memory do you have?

Sure, if your text file is many MB in size you might want to take some kind of paging approach on a grand scale, but anything less than 1MB should be entirely in memory IMO.

> I will have to read the required lines from the file and display it.
Just wait for all the complaints about your editor being so damn slow.
Reading the disk every key press is not the way to go.

> How many lines should I BUFFER in memory to represent the screen ?
Zero perhaps?
http://en.wikipedia.org/wiki/Model_view_controller
Make nice clear boundaries between input, edit actions and output. The core editor itself for example shouldn't give a hoot where the input is really coming from (the user or a macro replay), or where the output is going (ncurses, win32 GUI, etc).