I am on the process of making a shell . It has some functionalities and a little bit of signal handling. Now I want to know how in bash shell commands are repeated using an arrow key(u can see the previous command when u press the up arrow).Can anyone give me some idea?

Well I thought my post needed a revision. Consider the following code fragment:

#include <stdio.h>
#include <stdlib.h>

int main(){
char c = getchar();
printf("%c\t%d\n",c,c);
return 0;
}

Whenever I run this program the character I press a key to get a character. that character is echoed on terminal.Then again the char and its ascii value is printed.All I want is that the character is not echoed on the screen when I press it.For example with char 'a' I get printed:
a
a 97
but I want 'a 97' only.Is there a way of doing that?
Another thing,consider the same program with input of 'up arrow key'(not the string,for sure).It prints on terminal :
^[[A
> 27
=
'>
='(character is not entirely like that,but copying from terminal doesnot put the correct character)
Does some keys in the keyboard are handled some other way?

This fits better in the programming section.

You have to switch your terminal to raw mode; see man termios (function cfmakeraw()).

Further, when you press some keys (like arrows, home etc), multiple characters are placed in the input buffer.

hello Wim Sturkenboom. I've been thinking this for a while but does this mean that bash always receive encoded characters and no more raw input? I mean no more scan codes or the likes?

I think it does although I'm not sure.