I need to write a function to compare IP addresses

On Fri, 15 Aug 2003 01:29:26 -0400 in
<message-id:cd__a.739$3M4.380@lakeread04>
"Phil Powell" <soazine@erols.com> wrote:

> I have written a function that is supposed to compare the first three
> nodes of an IP address, but it is riddled with errors that I have
> given up trying to figure out.
>
> Is there an existing function out there that can do this? I want to
> compare"127.0.0.1" with "127.0.0.100" and come with as a "match", or
> "127.0.0.1" with "127.0.0.1", but no "match if "127.0.0.1" and
> "127.255.0.0".
>
> Here is what I have:


[ snip self-confessed non-working code ]


Phil,

Have a try with:


<?php
$ip1 = '127.0.0.1';
$ip2 = '127.0.0.100';
$ip3 = '127.255.0.0';


function ipcmp($ip_1, $ip_2) {
if (substr($ip_1, 0, strrpos($ip_1, '.')) ==
substr($ip_2, 0, strrpos($ip_2, '.'))
) {
return 'Match';
} else {
return 'No Match';
}
}

echo ipcmp($ip1, $ip2) . "<br />\n";
echo ipcmp($ip3, $ip2) . "<br />\n";
echo ipcmp($ip1, $ip3);
?>


HTH =)



Regards,

Ian

--
Ian.H [Design & Development]
digiServ Network - Web solutions
www.digiserv.net | irc.digiserv.net | forum.digiserv.net
Programming, Web design, development & hosting.

I plain give up. Your solution is so simple it's amazing and works, mine is
so complicated and fails.

Phil

"Ian.H [dS]" <ian@WINDOZEdigiserv.net> wrote in message
news:20030815070820.2dfa51f2.ian@WINDOZEdigiserv.n et...
> On Fri, 15 Aug 2003 01:29:26 -0400 in
> <message-id:cd__a.739$3M4.380@lakeread04>
> "Phil Powell" <soazine@erols.com> wrote:
>
> > I have written a function that is supposed to compare the first three
> > nodes of an IP address, but it is riddled with errors that I have
> > given up trying to figure out.
> >
> > Is there an existing function out there that can do this? I want to
> > compare"127.0.0.1" with "127.0.0.100" and come with as a "match", or
> > "127.0.0.1" with "127.0.0.1", but no "match if "127.0.0.1" and
> > "127.255.0.0".
> >
> > Here is what I have:
>
>
> [ snip self-confessed non-working code ]
>
>
> Phil,
>
> Have a try with:
>
>
> <?php
> $ip1 = '127.0.0.1';
> $ip2 = '127.0.0.100';
> $ip3 = '127.255.0.0';
>
>
> function ipcmp($ip_1, $ip_2) {
> if (substr($ip_1, 0, strrpos($ip_1, '.')) ==
> substr($ip_2, 0, strrpos($ip_2, '.'))
> ) {
> return 'Match';
> } else {
> return 'No Match';
> }
> }
>
> echo ipcmp($ip1, $ip2) . "<br />\n";
> echo ipcmp($ip3, $ip2) . "<br />\n";
> echo ipcmp($ip1, $ip3);
> ?>
>
>
> HTH =)
>
>
>
> Regards,
>
> Ian
>
> --
> Ian.H [Design & Development]
> digiServ Network - Web solutions
> www.digiserv.net | irc.digiserv.net | forum.digiserv.net
> Programming, Web design, development & hosting.

On Fri, 15 Aug 2003 04:30:48 -0400 in
<message-id:eT0%a.745$3M4.707@lakeread04>
"Phil Powell" <soazine@erols.com> wrote:

> I plain give up. Your solution is so simple it's amazing and works,
> mine is so complicated and fails.
>
> Phil


Don't give up Phil.. I been "messing around" with PHP for around 5 years
now.. it's great fun =)

IMO, you over-complicated your method by splitting the IP addresses into
separate numerical blocks. If you _really_ need to do some checking on
those values as INTs, then fair enough, if it's literally to compare the
first X chars, I just thought it'd be easier to work with as a complete
string.

Glad it works.. and FWIW.. I've posted some pretty "silly" questions
here before too.. sometimes, it's just a matter of not seeing the forest
for the trees =)



Regards,

Ian

--
Ian.H [Design & Development]
digiServ Network - Web solutions
www.digiserv.net | irc.digiserv.net | forum.digiserv.net
Programming, Web design, development & hosting.

> function ipcmp($ip_1, $ip_2) {
> if (substr($ip_1, 0, strrpos($ip_1, '.')) ==
> substr($ip_2, 0, strrpos($ip_2, '.'))
> ) {
> return 'Match';
> } else {
> return 'No Match';
> }
> }


Or a one-liner using the ternary operator, if you prefer, using Ian.H's
example:


function ipcmp($ip_1, $ip_2) {
return ((substr($ip_1, 0, strrpos($ip_1, '.')) == substr($ip_2, 0, strrpos($ip_2, '.'))) ? true : false);
}



Martin Lucas-Smith www.geog.cam.ac.uk/~mvl22
www.lucas-smith.co.uk

Senior Computing Technician (Web Technician)
Department of Geography, University of Cambridge (01223 3)33390

& Webmaster, SPRI
Scott Polar Research Institute, University of Cambridge

That's how I handled it, as a one-liner with the ternary operator!

Phil

"Martin Lucas-Smith" <mvl22@cam.ac.uk> wrote in message
newsine.SOL.4.44.0308151320160.23887-100000@green.csi.cam.ac.uk...
>
>
>
> > function ipcmp($ip_1, $ip_2) {
> > if (substr($ip_1, 0, strrpos($ip_1, '.')) ==
> > substr($ip_2, 0, strrpos($ip_2, '.'))
> > ) {
> > return 'Match';
> > } else {
> > return 'No Match';
> > }
> > }
>
>
> Or a one-liner using the ternary operator, if you prefer, using Ian.H's
> example:
>
>
> function ipcmp($ip_1, $ip_2) {
> return ((substr($ip_1, 0, strrpos($ip_1, '.')) == substr($ip_2, 0,
strrpos($ip_2, '.'))) ? true : false);
> }
>
>
>
> Martin Lucas-Smith www.geog.cam.ac.uk/~mvl22
> www.lucas-smith.co.uk
>
> Senior Computing Technician (Web Technician)
> Department of Geography, University of Cambridge (01223 3)33390
>
> & Webmaster, SPRI
> Scott Polar Research Institute, University of Cambridge
>
>
>

"Martin Lucas-Smith" <mvl22@cam.ac.uk> wrote:
>
> function ipcmp($ip_1, $ip_2) {
> return ((substr($ip_1, 0, strrpos($ip_1, '.')) ==
> substr($ip_2, 0, strrpos($ip_2, '.')))
> ? true : false);
> }

Why even bother with the ternary operator?

(boolean condition) ? true : false

is exactly equivalent to:

(boolean condition)

Ray