@@@ much mess, mostly manpages

[mLib] / utils / versioncmp.3.in

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+.\" -*-nroff-*-
+.\"
+.\" Manual for version number comparison
+.\"
+.\" (c) 2007, 2009, 2020, 2024 Straylight/Edgeware
+.\"
+.
+.\"----- Licensing notice ---------------------------------------------------
+.\"
+.\" This file is part of the mLib utilities library.
+.\"
+.\" mLib is free software: you can redistribute it and/or modify it under
+.\" the terms of the GNU Library General Public License as published by
+.\" the Free Software Foundation; either version 2 of the License, or (at
+.\" your option) any later version.
+.\"
+.\" mLib is distributed in the hope that it will be useful, but WITHOUT
+.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+.\" FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
+.\" License for more details.
+.\"
+.\" You should have received a copy of the GNU Library General Public
+.\" License along with mLib.  If not, write to the Free Software
+.\" Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+.\" USA.
+.
+.\"--------------------------------------------------------------------------
+.so ../defs.man \" @@@PRE@@@
+.
+.\"--------------------------------------------------------------------------
+.TH versioncmp 3mLib "6 January 2007" "Straylight/Edgeware" "mLib utilities library"
+.\" @versioncmp
+.\" @VERSIONCMP
+.
+.\"--------------------------------------------------------------------------
+.SH NAME
+versioncmp \- compare Debian-format version numbers
+.
+.\"--------------------------------------------------------------------------
+.SH SYNOPSIS
+.
+.nf
+.B "#include <mLib/versioncmp.h>"
+.PP
+.BI "int versioncmp(const char *" va ", const char *" vb ");"
+.BI "int VERSIONCMP(const char *" va ", " op ", const char *" vb ");"
+.fi
+.
+.\"--------------------------------------------------------------------------
+.SH DESCRIPTION
+.
+The
+.B versioncmp
+function compares version strings.
+.PP
+The format of version numbers considered is
+.IP
+.RI [ epoch
+.BR : ]
+.I main
+.RB [ \-
+.IR sub ]
+.PP
+The
+.I main
+part may contain colons or hyphens if there is an
+.I epoch
+or
+.IR sub ,
+respectively.  Version strings are compared componentwise: first epochs,
+then main parts, and finally subparts.
+.PP
+The component comparison is done as follows.  First, the initial
+subsequence of nondigit characters is extracted from each string, and
+these are compared lexicographically, using ASCII ordering, except that
+letters precede non-letters.  If both are the same, an initial sequence
+of digits is extracted from the remaining parts of the version strings,
+and these are compared numerically (an empty sequence being considered
+to have the value zero).  This process is repeated until we have a
+winner or until both strings are exhausted.
+.PP
+The return value is 0 if the two strings are equal, \-1 if
+.I va
+is older than
+.IR vb ,
+or +1 if
+.I va
+is newer than
+.IR vb .
+.PP
+The
+.B VERSIONCMP
+macro provides a more convenient syntax for the
+.B versioncmp
+function, by allowing a relational operator to be written between the
+operands.
+.
+.\"--------------------------------------------------------------------------
+.SH SEE ALSO
+.
+.BR mLib (3).
+.PP
+.IR "Debian Policy Manual" .
+.
+.\"--------------------------------------------------------------------------
+.SH AUTHOR
+.
+Mark Wooding, <mdw@distorted.org.uk>
+.
+.\"----- That's all, folks --------------------------------------------------