GETS(3) Linux Programmer's Manual GETS(3)
fgetc, fgets, getc, getchar, gets, ungetc - input of characters and
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 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 '\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 '\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
For non-locking 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.
ANSI - C, POSIX.1
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 asso-
ciated with the input stream; the results will be undefined and very
probably not what you want.
read(2), write(2), ferror(3), fopen(3), fread(3), fseek(3), puts(3),
GNU 1993-04-04 GETS(3)