It certainly is showing error but you're not looking for it. That's what scanf()'s return value is for, it returns 0 if it reads no values, 1 if it found 1 value, 2 for 2, etc. Each %... code counts as one "value".
The buffering thing is a known issue with scanf(). It's a "feature" -- it stops scanning at the first bad character -- which is pretty useless if you're not building a compiler.
fflush should work, if you tell it which stream to flush, which you are not. But the proper way to avoid these buffer problems is to not use scanf().
You can still use sscanf though, which is just as good without the problems! It scans a string, and has no buffer to leave things in.
Here's the usual way to do it:
Last edited by Corona688; 08-08-2014 at 12:18 PM..
When I worked with client-server (socket) programming, I encountered "the socket error# 10055" which means "No buffer space available". This might be a symptom of one or more applications that didn't return system resources (like memory) properly. Temporary solution was to reboot the machine to... (7 Replies)
how can i redirect standard input? i dont remember :/, though could you redirec not from a command? i mean, to redirect always stdin and stout (1 Reply)
PROGRAM A <-> PROGRAM B
PROGRAM A sends data as STDIN ro PROGRAM B and when PROGRAM B is executed from PROGRAM A, it sends output back to PROGRAM A. This is implemented using 2 pipes (fd1 & fd2).
The above process happens in a loop and during the second run, the previous data that had been... (10 Replies)
Hello,
I am having trouble clearing the serial port buffer using the iclear and iflush commands. The code runs without errors being returned, but when I check the buffer again there is still data.
The only way I have so far is to read until there is nothing left in the buffer. Shouldn't one... (1 Reply)
I have a program R installed on Ubuntu under /usr/bin/R. I also have a different version installed under /home/user/R. I would like to invoke the locally installed program temporarily. How can I do this automatically by running a script and then switching to the default program?
thanks,
SM (2 Replies)
Hi,
How can i clear the command. Suppose using esc k i retrieved teh command, but for some reason I want to clear and type fresh one... how can i do that.
thx (2 Replies)
I'm running a ksh script that requires user interaction, and said users (myself among them) may get a little trigger happy and get ahead of ourselves and accidentally key in the wrong responses to future prompts in the script.
Naturally, I'd like to prevent that, so how does one clear that... (0 Replies)
Hello everyone,
Can someone please explain the input buffer behaviour for the read command in ksh93 on AIX?
I have 'googled' for weeks now, and did not find a satisfactory answer or solution to my dilemma.
I have the following code:
STTY=$(stty -g)
if ;then
stty -echo -icanon time 0 min... (1 Reply)
Just started learning Unix and received my first assignment recently. We haven't learned many commands and honestly, I'm stumped. I'd like to receive assistance/guidance/hints.
1. The problem statement, all variables and given/known data:
How do I write a shell script that takes in a file or... (4 Replies)
Discussion started by: fozilla
4 Replies
LEARN ABOUT BSD
stdio
STDIO(3S)STDIO(3S)NAME
stdio - standard buffered input/output package
SYNOPSIS
#include <stdio.h>
FILE *stdin;
FILE *stdout;
FILE *stderr;
DESCRIPTION
The functions described in section 3S constitute a user-level buffering scheme. The in-line macros getc and putc(3S) handle characters
quickly. The higher level routines gets, fgets, scanf, fscanf, fread, puts, fputs, printf, fprintf, fwrite all use getc and putc; they can
be freely intermixed.
A file with associated buffering is called a stream, and is declared to be a pointer to a defined type FILE. Fopen(3S) creates certain
descriptive data for a stream and returns a pointer to designate the stream in all further transactions. There are three normally open
streams with constant pointers declared in the include file and associated with the standard open files:
stdin standard input file
stdout standard output file
stderr standard error file
A constant `pointer' NULL(0) designates no stream at all.
An integer constant EOF (-1) is returned upon end of file or error by integer functions that deal with streams.
Any routine that uses the standard input/output package must include the header file <stdio.h> of pertinent macro definitions. The func-
tions and constants mentioned in sections labeled 3S are declared in the include file and need no further declaration. The constants, and
the following `functions' are implemented as macros; redeclaration of these names is perilous: getc, getchar, putc, putchar, feof, ferror,
fileno.
SEE ALSO open(2), close(2), read(2), write(2), fread(3S), fseek(3S), f*(3S)
DIAGNOSTICS
The value EOF is returned uniformly to indicate that a FILE pointer has not been initialized with fopen, input (output) has been attempted
on an output (input) stream, or a FILE pointer designates corrupt or otherwise unintelligible FILE data.
For purposes of efficiency, this implementation of the standard library has been changed to line buffer output to a terminal by default and
attempts to do this transparently by flushing the output whenever a read(2) from the standard input is necessary. This is almost always
transparent, but may cause confusion or malfunctioning of programs which use standard i/o routines but use read(2) themselves to read from
the standard input.
In cases where a large amount of computation is done after printing part of a line on an output terminal, it is necessary to fflush(3S) the
standard output before going off and computing so that the output will appear.
BUGS
The standard buffered functions do not interact well with certain other library and system functions, especially vfork and abort.
LIST OF FUNCTIONS
Name Appears on Page Description
clearerr ferror.3s stream status inquiries
fclose fclose.3s close or flush a stream
fdopen fopen.3s open a stream
feof ferror.3s stream status inquiries
ferror ferror.3s stream status inquiries
fflush fclose.3s close or flush a stream
fgetc getc.3s get character or word from stream
fgets gets.3s get a string from a stream
fileno ferror.3s stream status inquiries
fopen fopen.3s open a stream
fprintf printf.3s formatted output conversion
fputc putc.3s put character or word on a stream
fputs puts.3s put a string on a stream
fread fread.3s buffered binary input/output
freopen fopen.3s open a stream
fscanf scanf.3s formatted input conversion
fseek fseek.3s reposition a stream
ftell fseek.3s reposition a stream
fwrite fread.3s buffered binary input/output
getc getc.3s get character or word from stream
getchar getc.3s get character or word from stream
gets gets.3s get a string from a stream
getw getc.3s get character or word from stream
printf printf.3s formatted output conversion
putc putc.3s put character or word on a stream
putchar putc.3s put character or word on a stream
puts puts.3s put a string on a stream
putw putc.3s put character or word on a stream
rewind fseek.3s reposition a stream
scanf scanf.3s formatted input conversion
setbuf setbuf.3s assign buffering to a stream
setbuffer setbuf.3s assign buffering to a stream
setlinebuf setbuf.3s assign buffering to a stream
sprintf printf.3s formatted output conversion
sscanf scanf.3s formatted input conversion
ungetc ungetc.3s push character back into input stream
4th Berkeley Distribution May 13, 1986 STDIO(3S)