The characters are exactly as documented - \b equates to a character code of 0x08 and \r equates to 0x0d. The thing that varies is how your OS reacts to those characters. Back when displays were trying to emulate an old teletype those actions were standardized, but they are less useful in modern environments and compatibility is not guaranteed.

Post by jonsca and tux4life have divulged all the information related to this topic.But would like to add some from my side. · Apart from the printable characters (character which can be seen on a output screen) we make use of several other operations when working on any text. When we work on a text editor,the text editor handles all the operations on its own and keeps us away from implementation details.But in C those operations are included in the character set itself so that a user can make use of them and format his/her output in any way required. · These characters which hold a very special meaning and work instead of functions as in text editors are your "Escape Characters". · Every letter has its identity. Say character 'A' instructs the machine to store value of 65 in 1 byte to symbolise 'A'. In escape characters we tell the compiler to escape or neglect the meaning of original character and act differently by placing the '\' symbol before it.Hence the name "Escape Character". You can try something like: · cout << "TestString1__TestString2"; · and place '\a' '\b' '\c' ... and so on and test what every character does.

What about a single space? ' ' ?

Backspace and tab both move the cursor position. Neither is truly a 'printable' character.

Your code says:

1. print "foo"
2. move the cursor back one space
3. move the cursor forward to the next tabstop
4. output "bar".

To get the output you expect, you need printf("foo\b \tbar"). Note the extra 'space'. That says:

1. output "foo"
2. move the cursor back one space
3. output a ' ' (this replaces the second 'o').
4. move the cursor forward to the next tabstop
5. output "bar".

Most of the time it is inappropriate to use tabs and backspace for formatting your program output. Learn to use printf() formatting specifiers. Rendering of tabs can vary drastically depending on how the output is viewed.

This little script shows one way to alter your terminal's tab rendering. Tested on Ubuntu + gnome-terminal:

#!/bin/bash
tabs -8 
echo -e "\tnormal tabstop"
for x in `seq 2 10`; do
  tabs $x
  echo -e "\ttabstop=$x"
 done

tabs -8
echo -e "\tnormal tabstop"

Also see man setterm and regtabs.

And if you redirect your output or just write to a file, tabs will quite commonly be displayed as fewer than the standard 8 chars, especially in "programming" editors and IDEs.

So in otherwords:

printf("%-8s%s", "foo", "bar"); /* this will ALWAYS output "foo     bar" */
printf("foo\tbar"); /* who knows how this will be rendered */

IMHO, tabs in general are rarely appropriate for anything. An exception might be generating output for a program that requires tab-separated-value input files (similar to comma separated value).

Backspace '\b' is a different story... it should never be used to create a text file since it will just make a text editor spit out garbage. But it does have many applications in writing interactive command line programs that cannot be accomplished with format strings alone. If you find yourself needing it a lot, check out "ncurses", which gives you much better control over where your output goes on the terminal screen. And typically, since it's 2011 and not 1995, a GUI is usually easier to deal with for highly interactive programs. But again, there are exceptions. Like writing a telnet server or console for a new scripting language.