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GETS(3)               DragonFly Library Functions Manual               GETS(3)


NAME

     gets - get a line from a stream


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <stdio.h>

     char *
     gets(char *str);


DESCRIPTION

     This interface is made obsolete by fgets(3) and gets_s(3).  See SECURITY
     CONSIDERATIONS below.

     The gets() function is equivalent to fgets(3) 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, gets() returns 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 gets() function does
     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 gets() function 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
     functionality through a buffer overflow attack.  It is strongly suggested
     that the fgets() and gets_s() functions be used in all cases.


SEE ALSO

     fgets(3), gets_s(3)


STANDARDS

     The gets() function conforms to ISO/IEC 9899:1999 ("ISO C99").

DragonFly 5.7-DEVELOPMENT      September 9, 2019     DragonFly 5.7-DEVELOPMENT
gets(n)                      Tcl Built-In Commands                     gets(n)

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NAME

       gets - Read a line from a channel


SYNOPSIS

       gets channelId ?varName?
______________________________________________________________________________


DESCRIPTION

       This command reads the next line from channelId, returns everything in
       the line up to (but not including) the end-of-line character(s), and
       discards the end-of-line character(s).

       ChannelId must be an identifier for an open channel such as the Tcl
       standard input channel (stdin), the return value from an invocation of
       open or socket, or the result of a channel creation command provided by
       a Tcl extension. The channel must have been opened for input.

       If varName is omitted the line is returned as the result of the
       command.  If varName is specified then the line is placed in the
       variable by that name and the return value is a count of the number of
       characters returned.

       If end of file occurs while scanning for an end of line, the command
       returns whatever input is available up to the end of file.  If
       channelId is in non-blocking mode and there is not a full line of input
       available, the command returns an empty string and does not consume any
       input.  If varName is specified and an empty string is returned in
       varName because of end-of-file or because of insufficient data in non-
       blocking mode, then the return count is -1.  Note that if varName is
       not specified then the end-of-file and no-full-line-available cases can
       produce the same results as if there were an input line consisting only
       of the end-of-line character(s).  The eof and fblocked commands can be
       used to distinguish these three cases.


EXAMPLE

       This example reads a file one line at a time and prints it out with the
       current line number attached to the start of each line.

              set chan [open "some.file.txt"]
              set lineNumber 0
              while {[gets $chan line] >= 0} {
                  puts "[incr lineNumber]: $line"
              }
              close $chan


SEE ALSO

       file(n), eof(n), fblocked(n), Tcl_StandardChannels(3)


KEYWORDS

       blocking, channel, end of file, end of line, line, non-blocking, read

Tcl                                   7.5                              gets(n)

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