NAME
gets — get a
string from a stdin stream
SYNOPSIS
char *gets(char *s);
DESCRIPTION
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.
The gets () function shall read
bytes from the standard input stream,
stdin, into the
array pointed to by s, until a <newline> is read or
an end-of-file condition is encountered. Any <newline> shall be
discarded and a null byte shall be placed immediately after the last byte
read into the array.
[CX] The gets ()
function may mark the last data access timestamp of the file associated with
stream for update. The last data access timestamp shall be
marked for update by the first successful execution of
fgetc(3), fgets(3),
fread(3), fscanf(3),
getc(3), getchar(3),
getdelim(3), getline(3),
gets (), or scanf(3) using
stream that returns data not supplied by a prior call to
ungetc(3).
RETURN VALUE
Upon successful completion, gets () shall
return s. If the end-of-file indicator for the stream is
set, or if the stream is at end-of-file, the end-of-file indicator for the
stream shall be set and gets () shall return a null
pointer. If a read error occurs, the error indicator for the stream shall be
set, gets () shall return a null pointer,
[CX] and set
errno to
indicate the error.
ERRORS
Refer to fgetc(3).
EXAMPLES
None.
APPLICATION USAGE
Reading a line that overflows the array pointed to by s results in undefined behavior. The use of fgets(3) is recommended.
Since the user cannot specify the length of the buffer passed to
gets (), use of this function is discouraged. The
length of the string read is unlimited. It is possible to overflow this
buffer in such a way as to cause applications to fail, or possible system
security violations.
Applications should use the fgets(3) function
instead of the obsolescent gets () function.
RATIONALE
The standard developers decided to mark the
gets () function as obsolescent even though it is in
the ISO C standard due to the possibility of buffer overflow.
FUTURE DIRECTIONS
The gets () function may be removed in a
future version.
SEE ALSO
V2_chap02(3), feof(3), ferror(3), fgets(3)
XBD <stdio.h>
CHANGE HISTORY
First released in Issue 1. Derived from Issue 1 of the SVID.
Issue 6
Extensions beyond the ISO C standard are marked.
Issue 7
Austin Group Interpretation 1003.1-2001 #051 is applied, clarifying the RETURN VALUE section.
The gets () function is marked
obsolescent.
Changes are made related to support for finegrained timestamps.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0257 [14] is applied.