GETS(3) Linux Programmer's Manual GETS(3)
fgetc, fgets, getc, getchar, gets, ungetc - input of characters and strings
int fgetc(FILE *stream);
char *fgets(char *s, int size, FILE *stream);
int getc(FILE *stream);
char *gets(char *s);
int ungetc(int c, FILE *stream);
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 evalu-
ates 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 subse-
quent 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).
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.
C89, C99, POSIX.1-2001.
LSB deprecates gets(). POSIX.1-2008 marks gets() obsolescent. ISO C11 removes the speci-
fication 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.
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.
read(2), write(2), ferror(3), fgetwc(3), fgetws(3), fopen(3), fread(3), fseek(3), get-
line(3), getwchar(3), puts(3), scanf(3), ungetwc(3), unlocked_stdio(3), fea-
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GNU 2012-01-18 GETS(3)