Thread: what is echo???

I know this is a stupid question but i am learning by myself so...here we go.
I was reading about getch and getchar functions and difference between them but failed to understand what echo means here-
getch - Reads a character directly from the console without buffer, and without echo.
getchar - Reads a character directly from the console without buffer, but with echo.

1. Does it mean printing to screen?
if it does, then why i am not seeing so?. Please give me some working example code.
or
2. Does it mean returning the value?
or
3. Above explanations are wrong!

I am totally confused please help me!!!

EDIT: 1. above explanations of getch and getchar were taken from here-
http://en.wikipedia.org/wiki/Conio.h
http://en.wikibooks.org/wiki/C_Progr...erence/conio.h

2. I am using Orwell Dev-c++ Ide with TDM-GCC-4.8.1 on windows xp.

Originally Posted by gemera

A quick google on getch :

getch in c language: getch function prompts the user to press a character and that character is not printed on screen, getch header file is conio.h.

Thanks for replying..

but printing to screen part was meant for getchar, as the line says above in my first post-
getchar - Reads a character directly from the console without buffer, but with echo.
getch - Reads a character directly from the console without buffer, and without echo.

so if without echo meant not printed on screen then with echo should meant printed on screen according to your statement which is not happening as i mentioned.

It maybe because of any number of reason- such as-
-source of info as in wiki article is outdated or
-code needed some additional header files or
-this description was meant for older windows systems

in any case, I am stuck!

Originally Posted by bkd

but printing to screen part was meant for getchar, as the line says above in my first post(getchar - Reads a character directly from the console without buffer, but with echo.).
This echo part is confusing me of getchar() function not the getch().

The documentation that you quoted says "without echo" for getch (which I note is non-standard). gemera's response for getch is that "without echo" means "not printed on screen". Logically, this means that "with echo" means "printed on screen", which answers your question about getchar.

If you still don't understand, then write a program (or two) that uses getch and getchar and experiment for yourself. You probably are seeing the text printed on screen for getchar, but you merely misunderstand what that means in this context. (Or maybe you're piping input from somewhere, so you don't see the echo because it doesn't apply in that context.)

EDIT:
Ugh, and I note that you're talking about getche, not getchar. getche is also non-standard, but then that's the nature of conio.h

@laselight
i did write...but sadly its not working according to the description given on those wiki articles.
for example-

Code:

#include <stdio.h>
#include <conio.h>

int main()
{
    int input;

    printf("Input a character then press return: ");
    input = getchar();
    
    return 0;
}

above code suppose to echo any character i enter(letter, number and special etc..) but its not.
before anybody says that i am suppose to use char at the place of int, let me tell you i did try that and it didn't work.

EDIT:
I even run above code on turbo c++ IDE still nothing.
Does no body uses windows here or what? if you do, please try on your system and tell me the result.
How do i know if i am in fact piping input?

Originally Posted by bkd

above code suppose to echo any character i enter(letter, number and special etc..) but its not.

It does: when you type any (printable) character, it appears on screen. However, it appears on screen even before you press enter. I assumed that was what the documentation meant by "echo", but then I realised that you were confusing getchar with getche. Therefore, in your test program, this is wrong:

Code:

input = getchar();

If I remember correctly, it should be:

Code:

input = getche();

The expected behaviour then would be that when you type any character, it is read, and at the same time it appears on screen (without having to press enter). This appearing of the character on screen is the "echo".

EDIT:

Originally Posted by bkd

What are you talking about getche? i did meant getchar.

If you mean getchar, then you're looking at the wrong documentation. Read the wiki articles that you linked to:

Code:

getche - Reads a character directly from the console without buffer, but with echo.

Code:

int getche(void) 	Reads a character directly from the console without buffer, but with echo.

No info on getchar to see here.

Originally Posted by bkd

I read them again and find a line which says that It echo to stdout. Which not necessarily meant monitor or any other screen right?

Yes, stdout does not necessarily mean that there is actually a screen.

I'm not sure that conio.h functions are made to work with stdin and stdout. They are strictly designed for use with the console (thus the name, and thus the C Standards won't let them be standard - they are IO specific, instead of the generic that the Standard adheres to.

In this program, getche() (which should echo to the console), will echo, but with a slight change, it will show nothing.

Code:

#include <stdio.h>
#include <conio.h>

int main() {
   int mychar;

   mychar=getche();

   //if you include the getchar(), then getche() will succeed.
   //remove it and recompile, and getche() will show nothing
   // on the console.
   getchar();


   //this print line has priority on printing to the console. 
   //Without the getchar(), getche() line just above, will be usurped, in Win 7.
   printf("mychar: %c\n",mychar);  //this just proves that your
   //console is working OK, is stdout, and mychar received the value
   
   getchar(); //stops the program from disappearing too quickly.
   return 0;
}

Echo just means "print on the console". They couldn't use the word print because that was used to route output to the printer.