getchar

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 a null byte
       ('\0').  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 terminating null byte ('\0') 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 nonlocking 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
       C89, C99, POSIX.1-2001.

       LSB deprecates gets().  POSIX.1-2008 marks gets() obsolescent.  ISO C11
       removes the specification of gets() from the C language, and since
       version 2.16, glibc header files don't expose the function declaration
       if the _ISOC11_SOURCE feature test macro is defined.

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(2) for the file descriptor
       associated with the input stream; the results will be undefined and
       very probably not what you want.

SEE ALSO
       read(2), write(2), ferror(3), fgetwc(3), fgetws(3), fopen(3), fread(3),
       fseek(3), getline(3), getwchar(3), puts(3), scanf(3), ungetwc(3),
       unlocked_stdio(3), feature_test_macros(7)

COLOPHON
       This page is part of release 3.55 of the Linux man-pages project.  A
       description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.




GNU                               2012-01-18                           GETS(3)