Sponsored Content
Full Discussion: getchar()
Top Forums UNIX for Dummies Questions & Answers getchar() Post 8296 by Perderabo on Tuesday 9th of October 2001 03:24:38 PM
Old 10-09-2001
You will need to reprogram your tty driver to do what you want. You will need to disable line processing, input processing, and signal generation to get that "any key" part working. The exact details vary depending on your tty driver. But it is probably documented on the termio man page.

You will do one ioctl to get the current params, change some, then do a second ioctl to put them back.

Something like this:

struct termio modes;

ioctl(fd, TCGETA, (char *) &modes);

modes.c_lflag &= ~(ISIG|ICANON);
modes.c_cc[VMIN] = 1;
modes.c_cc[VTIME] = 1;

ioctl(fd, TCSETA. (char *) &modes);

Now, I'm not sure if I got this right for my system let alone yours, but it should get you started.

You have a second problem in that getchar and printf are buffered. I think that your getchar would work but the printf won't output anything unless it happens to fill the buffer. So you will need to call setvbuf to set fd 1 to completely non-buffered.
 

5 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Bash replacement to getchar

There's a replacement in bash for getchar or get functions of C and C++?Those functions read the next char avaliable in the input stream. I've tried something like: OLD_STTY=`stty -g` stty cbreak -echo look=`dd if=/dev/tty bs=1 count=1 2>/dev/null` stty $OLD_STTY But it is not working... (3 Replies)
Discussion started by: Asafe
3 Replies

2. Programming

How to skip getchar in C?

Hi, I would like to read an input from keyboard using getchar. However, if no input (No Carriage return/new line none whatsoever) is given after say, 5 seconds, I would like to skip the getchar and move on. How do I do this in C. I'm using GNU compiler set. Thanks, (5 Replies)
Discussion started by: cprogdude
5 Replies

3. Programming

Help on getchar

I wanted to make a simple program that writes chracters in a file but i didnt want to press enter .So i found the getchar which doesnt need enter.If i pass (int) getchar to putc ,in the file it shows a P character.The (int) getchar says it is equal to1734747216 so i do (int) getchar-1734747216... (4 Replies)
Discussion started by: fireblast
4 Replies

4. Programming

How to kill disowned process which calls getchar() in code

Hi, What happens to process state when getchar() is called? I wrote a C code in which I call getchar() somewhere down the road. I forgot about that, I started the process, put it in bg and disowned it using "disown". Now, how do I see where that process has gone/how do kill it? Thanks, Amrut (1 Reply)
Discussion started by: 17amrut29
1 Replies

5. Programming

What is the difference between printf and putchar() or scanf and getchar() ?

Im a newbie to programming language, i found tat there r these function called printf and putchar() as well as scanf and getchar(), im curious abt why do dey hav these 2 different function although dey r doing the same instruction? :confused: (13 Replies)
Discussion started by: kris26
13 Replies
GETS(3) 						     Linux Programmer's Manual							   GETS(3)

NAME
fgetc, fgets, getc, getchar, gets, ungetc - input of characters and strings SYNOPSIS
#include <stdio.h> int fgetc(FILE *stream); char *fgets(char *s, int size, FILE *stream); int getc(FILE *stream); int getchar(void); char *gets(char *s); int ungetc(int c, FILE *stream); DESCRIPTION
fgetc() reads the next character from stream and returns it as an unsigned char cast to an int, or EOF on end of file or error. getc() is equivalent to fgetc() except that it may be implemented as a macro which evaluates stream more than once. getchar() is equivalent to getc(stdin). gets() reads a line from stdin into the buffer pointed to by s until either a terminating newline or EOF, which it replaces with ''. No check for buffer overrun is performed (see BUGS below). fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A '' is stored after the last character in the buffer. ungetc() pushes c back to stream, cast to unsigned char, where it is available for subsequent read operations. Pushed - back characters will be returned in reverse order; only one pushback is guaranteed. Calls to the functions described here can be mixed with each other and with calls to other input functions from the stdio library for the same input stream. For non-locking counterparts, see unlocked_stdio(3). RETURN VALUE
fgetc(), getc() and getchar() return the character read as an unsigned char cast to an int or EOF on end of file or error. gets() and fgets() return s on success, and NULL on error or when end of file occurs while no characters have been read. ungetc() returns c on success, or EOF on error. CONFORMING TO
ANSI - C, POSIX.1 BUGS
Never use gets(). Because it is impossible to tell without knowing the data in advance how many characters gets() will read, and because gets() will continue to store characters past the end of the buffer, it is extremely dangerous to use. It has been used to break computer security. Use fgets() instead. It is not advisable to mix calls to input functions from the stdio library with low - level calls to read() for the file descriptor associ- ated with the input stream; the results will be undefined and very probably not what you want. SEE ALSO
read(2), write(2), ferror(3), fopen(3), fread(3), fseek(3), puts(3), scanf(3), unlocked_stdio(3) GNU
1993-04-04 GETS(3)
All times are GMT -4. The time now is 09:52 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy