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Programming
Scanf problem under LINUX...
Post 19764 by robotronic on Tuesday 16th of April 2002 02:37:47 PM
04-16-2002
Well, if I use scanf("%s", &Ch) the program works correctly, but the 'enter' character and the terminating character '\0' where are stored?
Isn't this an error? Don't these two characters overwrite the two bytes of memory next to the "Ch" variable?
If the method you shown me is ok, then when do we need to use "%c" or other functions that reads only a character (like getchar) ?
I still don't understand...
Another question: I want to read a string, scanning also spaces and tabs and check the length (and if necessary prompt the user to re-enter the string). Is the use of fgets followed by sscanf the best method I can use? Or are there any better methods?
Thanks a lot for your help!
Isn't this an error? Don't these two characters overwrite the two bytes of memory next to the "Ch" variable?
If the method you shown me is ok, then when do we need to use "%c" or other functions that reads only a character (like getchar) ?
I still don't understand...
Another question: I want to read a string, scanning also spaces and tabs and check the length (and if necessary prompt the user to re-enter the string). Is the use of fgets followed by sscanf the best method I can use? Or are there any better methods?
Thanks a lot for your help!
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LEARN ABOUT OPENSOLARIS
gets
gets(3C) Standard C Library Functions gets(3C) NAME
gets, fgets - get a string from a stream SYNOPSIS
#include <stdio.h> char *gets(char *s); char *fgets(char *s, int n, FILE *stream); DESCRIPTION
The gets() function reads bytes from the standard input stream (see Intro(3)), stdin, into the array pointed to by s, until a newline char- acter is read or an end-of-file condition is encountered. The newline character is discarded and the string is terminated with a null byte. If the length of an input line exceeds the size of s, indeterminate behavior may result. For this reason, it is strongly recommended that gets() be avoided in favor of fgets(). The fgets() function reads bytes from the stream into the array pointed to by s, until n-1 bytes are read, or a newline character is read and transferred to s, or an end-of-file condition is encountered. The string is then terminated with a null byte. The fgets() and gets() functions may mark the st_atime field of the file associated with stream for update. The st_atime field will be marked for update by the first successful execution of fgetc(3C), fgets(), fread(3C), fscanf(3C), getc(3C), getchar(3C), gets(), or scanf(3C) using stream that returns data not supplied by a prior call to ungetc(3C) or ungetwc(3C). RETURN VALUES
If end-of-file is encountered and no bytes have been read, no bytes are transferred to s and a null pointer is returned. For standard-con- forming (see standards(5)) applications, if the end-of-file indicator for the stream is set, no bytes are transferred to s and a null pointer is returned whether or not the stream is at end-of-file. If a read error occurs, such as trying to use these functions on a file that has not been opened for reading, a null pointer is returned and the error indicator for the stream is set. If end-of-file is encoun- tered, the EOF indicator for the stream is set. Otherwise s is returned. ERRORS
Refer to fgetc(3C). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
lseek(2), read(2), ferror(3C), fgetc(3C), fgetwc(3C), fopen(3C), fread(3C), getchar(3C), scanf(3C), stdio(3C), ungetc(3C), ungetwc(3C), attributes(5), standards(5) SunOS 5.11 15 Oct 2003 gets(3C)