This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding Linux
manual page for details of Linux behavior), or the interface may not be
implemented on Linux.
gets — get a string from a stdin stream
char *gets(char *s);
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.
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(), fgets(), fread(), fscanf(),
getc(), getchar(), getdelim(), getline(),
gets(), or scanf() using stream that returns data not
supplied by a prior call to ungetc().
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, and set errno to indicate the error.
Refer to fgetc().
The following sections are informative.
Reading a line that overflows the array pointed to by s results in
undefined behavior. The use of fgets() 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() function instead of the
obsolescent gets() function.
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.
The gets() function may be removed in a future version.
Section 2.5, Standard I/O Streams, feof(),
The Base Definitions volume of POSIX.1‐2017,
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1-2017, Standard for Information Technology -- Portable Operating
System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018
Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html .
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