diff options
| author | dkf <donal.k.fellows@manchester.ac.uk> | 2004-05-28 12:40:29 (GMT) |
|---|---|---|
| committer | dkf <donal.k.fellows@manchester.ac.uk> | 2004-05-28 12:40:29 (GMT) |
| commit | 4c592a9067ad846bafeecd1bbe492053470bb4f6 (patch) | |
| tree | 689e3a0776b3940c41492929036d3fd5a6e40367 /doc/tell.n | |
| parent | 0cb68aa767f2457c65b8cbc4d27c29545da80744 (diff) | |
| download | tcl-4c592a9067ad846bafeecd1bbe492053470bb4f6.zip tcl-4c592a9067ad846bafeecd1bbe492053470bb4f6.tar.gz tcl-4c592a9067ad846bafeecd1bbe492053470bb4f6.tar.bz2 | |
Added example
Diffstat (limited to 'doc/tell.n')
| -rw-r--r-- | doc/tell.n | 16 |
1 files changed, 15 insertions, 1 deletions
@@ -5,7 +5,7 @@ '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: tell.n,v 1.5 2001/09/14 19:20:40 andreas_kupries Exp $ +'\" RCS: @(#) $Id: tell.n,v 1.6 2004/05/28 12:48:36 dkf Exp $ '\" .so man.macros .TH tell n 8.1 Tcl "Tcl Built-In Commands" @@ -34,6 +34,20 @@ Tcl standard channel (\fBstdin\fR, \fBstdout\fR, or \fBstderr\fR), the return value from an invocation of \fBopen\fR or \fBsocket\fR, or the result of a channel creation command provided by a Tcl extension. .VE +.SH EXAMPLE +Read a line from a file channel only if it starts with \fBfoobar\fR: + +.CS +# Save the offset in case we need to undo the read... +set offset [\fBtell\fR $chan] +if {[read $chan 6] eq "foobar"} { + gets $chan line +} else { + set line {} + # Undo the read... + seek $chan $offset +} +.CE .SH "SEE ALSO" file(n), open(n), close(n), gets(n), seek(n), Tcl_StandardChannels(3) |