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Crafting text editor

  1. May 12, 2005 #1


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    Hi Ho! ^^

    I'm still learning programming in C (I'm still on my first year in Information Technology faculty)
    Well, I'm interested in making something from scratch.
    Hehehe... right now I'm curious about efficient text handling technique used in a text editor.

    When creating a simple text editor, I create a temporary array of char in C.
    It is: char *charInput[ 1000 ];
    I hope the user doesn't type longer than 999 characters.
    Then when the user press ENTER, I'll copy the content of the charInput into a file.
    That's my idea to handle the text. I know this is a bad one because:
    1. If the user input a text longer than 1000 (e.g. DNA chain code), my charInput can't accommodate it.
    2. Time consuming of IO operation when the user press ENTER or ARROW key to navigate the screen because my program always read the file from HD.
    3. charInput is such a waste of space because it reserves 1000 bytes in memory although the user only type 3 characters.

    From my data structures course, I've an idea to create a linklist for every character which is typed. But this is a bad idea because it will waste more space for the pointer.

    Yesterday I browsed through the Internet searching an efficient method for this problem. Unfortunately, I didn't find it.
    But I've had some information.

    According to you, does Emacs has the most efficient text handling method?
    I've read several articles on Emacs and downloaded the source code from FSF.
    I wonder how Emacs handles text using its buffer. The structure for buffer in buffer.h only contain some int variables. So, where's the text if it is not written directly to the file? (I read that Emacs buffer is on the main memory, not in HD)
    So, could you please give me an information about how actually Emacs handles the text using the buffer?

    Do you have any suggestions where I must go to find out more about text handling technique?

    Mmm... sorry if I'm not straight to the point but I just want to explain my situation.

    Thank you very much for helping me, guys!
    Last edited: May 12, 2005
  2. jcsd
  3. May 12, 2005 #2
    You will need to use a dynamic array. You are currently creating an array with 1000 holes that can be filled with letters. A better solution is to create an array with one hole and simple add holes as needed. To do this you will need to look into reallocating array space to grow or shrink as needed.


    Also you will want to use a buffer(memory) to store your work. Don't read/write every letter as it is typed to a file because that is very inefficient as you have found out.

    Look at the code for the pico text editor. It is much smaller than emacs but still very powerful. You might also try reading the code for vim.

    Good luck.
  4. May 12, 2005 #3
    I would recommend going even simpler than pico or vim. Basically at first you want to get away from anything even related to a terminal (because this is where things get most complicated). I would start with ed.
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