What is the tab width (number of spaces indented for a tab) within code tags? Is it 8? Is it possible to change it to 4? Since the code is wrapped for lines with length less than 80 characters, I think that it is a waste of space.

Just testing. I used Notepad to create the above text

My suggestion is to change the option in your text editor to convert tabs to spaces because some people might use 8 spaces while others 4 or some other number. I've even seen just 2 spaces.

Perhaps have an option to set the tab stop explicitly in the code tags:
[code=c, tab=2]
#include <stdio.h>

int main ( void )
{
puts ( "Hello, world!" );
return 0;
}
[/code]

CSS 2 doesn't appear to have a tab-width property. The following are the properties that can be applied to text elements: http://www.w3schools.com/css/css_reference.asp#text

I know that if I use the option to replace tabs with 4 spaces (which I already do in Visual Studio), this problem would be over for my code. But we do not have control of the other user's editors. When they post codes with the tab character used for indenting, even code with a level 4 nesting can wrap unnecessarily. Sometimes I copy and paste the code to my own editor and replace tabs with 4 spaces to make the code readable, and was wondering if there was a quick fix. But if as Dani says that nothing can be done about it, well I guess we should grin and bear.

I believe it is a platform-specific setting ... i.e. Your OS/browser determines how many spaces per tab.

Gah, I hate when this happens! I was googling to see if there is a solution or workaround to this problem, only to find something that was specifically what I was looking for. I click on it and it ended up being this very thread.

I'm not going to try to pretend that I'm any sort of web programming expert, but couldn't you modify your parser to change tab characters into spaces? That way you could specify a manual tab width within the code tags, like Narue suggested.

That's a very brute force method that would undermine the purpose of tabs, screwing up more things than it fixes. For example, if tabs were to be converted into two spaces, the following:

Would be translated, without the poster's intent, into:

C'mon Dani, you can't fool me; I know you can do it. How hard would it be to make your parser calculate the number of spaces to insert to make it line up to the next tab stop?