NAME

gets - get a string from a stdin stream

SYNOPSIS

[OB] #include <stdio.h>

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(), fgets(), fread(), fscanf(), getc(), getchar(), getdelim(), getline(), gets(), or scanf() using stream that returns data not supplied by a prior call to ungetc().

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.

EXAMPLES

None.

APPLICATION USAGE

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.

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

Standard I/O Streams, feof, ferror, fgets

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.