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fgets(3)                 BSD Library Functions Manual                 fgets(3)


NAME

     fgets, gets -- get a line from a stream


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <stdio.h>

     char *
     fgets(char * restrict str, int size, FILE * restrict stream);

     char *
     gets(char *str);


DESCRIPTION

     The fgets() function reads at most one less than the number of characters
     specified by size from the given stream and stores them in the string
     str.  Reading stops when a newline character is found, at end-of-file or
     error.  The newline, if any, is retained.  If any characters are read and
     there is no error, a `\0' character is appended to end the string.

     The gets() function is equivalent to fgets() with an infinite size and a
     stream of stdin, except that the newline character (if any) is not stored
     in the string.  It is the caller's responsibility to ensure that the
     input line, if any, is sufficiently short to fit in the string.


RETURN VALUES

     Upon successful completion, fgets() and gets() return a pointer to the
     string.  If end-of-file occurs before any characters are read, they
     return NULL and the buffer contents remain unchanged.  If an error
     occurs, they return NULL and the buffer contents are indeterminate.  The
     fgets() and gets() functions do not distinguish between end-of-file and
     error, and callers must use feof(3) and ferror(3) to determine which
     occurred.


ERRORS

     [EBADF]            The given stream is not a readable stream.

     The function fgets() may also fail and set errno for any of the errors
     specified for the routines fflush(3), fstat(2), read(2), or malloc(3).

     The function gets() may also fail and set errno for any of the errors
     specified for the routine getchar(3).


SECURITY CONSIDERATIONS

     The gets() function cannot be used securely.  Because of its lack of
     bounds checking, and the inability for the calling program to reliably
     determine the length of the next incoming line, the use of this function
     enables malicious users to arbitrarily change a running program's func-
     tionality through a buffer overflow attack.  It is strongly suggested
     that the fgets() function be used in all cases.  (See the FSA.)


SEE ALSO

     feof(3), ferror(3), fgetln(3), fgetws(3), getline(3)


STANDARDS

     The functions fgets() and gets() conform to ISO/IEC 9899:1999
     (``ISO C99'').

BSD                              June 4, 1993                              BSD

Mac OS X 10.8 - Generated Mon Aug 27 18:14:25 CDT 2012