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 '\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 buf-
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 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 associated 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), scanf(3),
GNU 1993-04-04 GETS(3)