switch with case 0

From	Fiver <numeralfive@gmail.com>
Newsgroups	comp.lang.php
Subject	switch with case 0
Date	2013-08-17 06:55 +0200
Organization	A noiseless patient Spider
Message-ID	<kumvo8$lel$1@dont-email.me> (permalink)

Show all headers | View raw

This example

  switch ("foo") {
    case 0:
      echo "'foo' is 0\n";
      break;
    default:
      echo "'foo' is not 0\n";
  }

will print: 'foo' is 0.

I know how to avoid the problem, I'm just wondering what kind of
comparison is used that makes "foo" equal to 0? The manual mentions
"loose comparison", but this is even looser than usual.

By the way, the original code was meant to validate SORT_* arguments.
It's a little harder to spot here:

  switch ($mode) {
    case SORT_ASC:
    case SORT_DESC:
    case SORT_REGULAR:
    case SORT_NUMERIC:
    case SORT_STRING:
    case SORT_LOCALE_STRING:
    case SORT_NATURAL:
    case SORT_FLAG_CASE:
      break;
    default:
      throw new \InvalidArgumentException("invalid sort mode: $mode");
  }

SORT_REGULAR is 0, so if the input is a string, this will break (literally).


regards,
5er

Back to comp.lang.php | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

switch with case 0 Fiver <numeralfive@gmail.com> - 2013-08-17 06:55 +0200
  Re: switch with case 0 "J.O. Aho" <user@example.net> - 2013-08-17 08:35 +0200
    Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 08:29 +0100
    Re: switch with case 0 Luuk <luuk@invalid.lan> - 2013-08-17 09:51 +0200
    Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 13:16 +0200
      Re: switch with case 0 "Peter H. Coffin" <hellsop@ninehells.com> - 2013-08-17 10:56 -0500
        Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 17:45 +0100
          Re: switch with case 0 Tim Streater <timstreater@greenbee.net> - 2013-08-17 18:58 +0100
            Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 19:39 +0100
              Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 21:36 +0200
        Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 22:14 +0200
      Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 13:56 -0400
        Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 21:55 +0200
          Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-17 21:04 +0100
            Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-17 22:32 +0200
              Re: switch with case 0 Richard Yates <richard@yatesguitar.com> - 2013-08-17 15:20 -0700
            Re: switch with case 0 Fiver <numeralfive@gmail.com> - 2013-08-17 22:37 +0200
              Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 19:26 -0400
              Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-18 12:54 +0100
          Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 20:23 -0400
            Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-18 15:22 +0200
              Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 11:20 -0400
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-18 18:28 +0200
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 15:16 -0400
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 18:04 -0400
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 00:17 +0200
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 00:13 +0200
                Re: switch with case 0 The Natural Philosopher <tnp@invalid.invalid> - 2013-08-19 00:35 +0100
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-19 06:30 -0400
                Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-18 22:13 -0400
                Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 19:55 +0200
          Re: switch with case 0 Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-08-19 10:18 +0200
            Re: switch with case 0 Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2013-08-19 19:39 +0200
  Re: switch with case 0 Fiver <numeralfive@gmail.com> - 2013-08-17 16:15 +0200
  Re: switch with case 0 Norman Peelman <npeelman@cfl.rr.com> - 2013-08-17 13:28 -0400

csiph-web