Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.php > #3198 > unrolled thread

Setting variable to false in a WHILE loop

Back to article view | Back to comp.lang.php

Contents

  Setting variable to false in a WHILE loop jwcarlton <jwcarlton@gmail.com> - 2011-09-23 20:53 -0700
    Re: Setting variable to false in a WHILE loop Jerry Stuckle <jstucklex@attglobal.net> - 2011-09-24 09:14 -0400
      Re: Setting variable to false in a WHILE loop tamouse <tamouse.lists@gmail.com> - 2011-09-28 11:28 -0700
        Re: Setting variable to false in a WHILE loop Tim Streater <timstreater@greenbee.net> - 2011-09-28 20:49 +0100
        Re: Setting variable to false in a WHILE loop Doug Miller <doug_at_milmacdotcom@example.com> - 2011-09-29 08:09 -0400
        Re: Setting variable to false in a WHILE loop Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-01 16:08 +0200

#3198 — Setting variable to false in a WHILE loop

I'm doing a MySQL query, then running a WHILE loop on it, like so:

while (list($id, $title, $text) = mysql_fetch_row($sth)) {
  if ($text) {
    // do whatever
  }
}

The problem that I'm having is that sometimes, it's possible for $text
to equal "" instead of NULL. I use it as a quick way to check whether
the row is new (in which case $text is NULL), or if it's been updated
(in which case $text is ""), without requiring an additional field.

I know that I could just say:

if ($text && ($text != "")) {

And I could move the list() inside of the loop, like so:

while ($row = mysql_fetch_row($sth) {
  $text = false;
  list($id, $title, $text) = $row;

  if ($text) {
    // do whatever
  }
}


But I'm curious if there's a way to reset $id, $title, and $text to
false at the beginning of the loop. Something like:

// Just a mock-up, using "my" from Perl
while (my(list($id, $title, $text)) = mysql_fetch_row($sth)) {

[toc] | [next] | [standalone]

#3200

On 9/23/2011 11:53 PM, jwcarlton wrote:
> I'm doing a MySQL query, then running a WHILE loop on it, like so:
>
> while (list($id, $title, $text) = mysql_fetch_row($sth)) {
>    if ($text) {
>      // do whatever
>    }
> }
>
> The problem that I'm having is that sometimes, it's possible for $text
> to equal "" instead of NULL. I use it as a quick way to check whether
> the row is new (in which case $text is NULL), or if it's been updated
> (in which case $text is ""), without requiring an additional field.
>
> I know that I could just say:
>
> if ($text&&  ($text != "")) {
>
> And I could move the list() inside of the loop, like so:
>
> while ($row = mysql_fetch_row($sth) {
>    $text = false;
>    list($id, $title, $text) = $row;
>
>    if ($text) {
>      // do whatever
>    }
> }
>
>
> But I'm curious if there's a way to reset $id, $title, and $text to
> false at the beginning of the loop. Something like:
>
> // Just a mock-up, using "my" from Perl
> while (my(list($id, $title, $text)) = mysql_fetch_row($sth)) {
>

Why complicate things?  Why not just use

  if ($text !== false)


-- 
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

[toc] | [prev] | [next] | [standalone]

#3224

On Saturday, September 24, 2011 8:14:46 AM UTC-5, Jerry Stuckle wrote:
> Why complicate things?  Why not just use
> 
>   if ($text !== false)

That works, but might be a little opaque. I'd use:

  if (!empty($text))

As it's a little more clear to the reader/maintainer.

Also, with the === & !== idiom, isn't it better reverse the operands, thus:

  if (FALSE !== $text)

?

[toc] | [prev] | [next] | [standalone]

#3229

In article 
<9281403.1198.1317234500379.JavaMail.geo-discussion-forums@yqma37>,
 tamouse <tamouse.lists@gmail.com> wrote:

> On Saturday, September 24, 2011 8:14:46 AM UTC-5, Jerry Stuckle wrote:
> > Why complicate things?  Why not just use
> > 
> >   if ($text !== false)
> 
> That works, but might be a little opaque. I'd use:
> 
>   if (!empty($text))
> 
> As it's a little more clear to the reader/maintainer.
> 
> Also, with the === & !== idiom, isn't it better reverse the operands, thus:
> 
>   if (FALSE !== $text)

This business of doing:

  if  (27===$myvar) ...

is the dopiest thing I ever heard of. 27 is equal to 27, end of. People 
should really learn that the computer serves *them*, not the other way 
around.

-- 
Tim

"That excessive bail ought not to be required, nor excessive fines imposed,
nor cruel and unusual punishments inflicted"  --  Bill of Rights 1689

[toc] | [prev] | [next] | [standalone]

#3232

On 9/28/2011 2:28 PM, tamouse wrote:

> Also, with the ===&  !== idiom, isn't it better reverse the operands, thus:
>
>    if (FALSE !== $text)
>
Why would you think that such a grossly counterintuitive construct is 
better than the clear and obvious
	if ($text !== FALSE)
?

[toc] | [prev] | [next] | [standalone]

#3251

tamouse wrote:

> On Saturday, September 24, 2011 8:14:46 AM UTC-5, Jerry Stuckle wrote:
>> Why complicate things?  Why not just use
>> 
>>   if ($text !== false)
> 
> That works, but might be a little opaque. I'd use:
> 
>   if (!empty($text))
> 
> As it's a little more clear to the reader/maintainer.

It is not equivalent, though:

<http://php.net/empty>

> Also, with the === & !== idiom, isn't it better reverse the operands,
> thus:
> 
>   if (FALSE !== $text)
> 
> ?

No.  Why should it be?

(The PEAR Coding Standards also actively recommend against writing `false'
as `FALSE': <http://pear.php.net/manual/en/standards.naming.php>)


PointedEars
-- 
Anyone who slaps a 'this page is best viewed with Browser X' label on
a Web page appears to be yearning for the bad old days, before the Web,
when you had very little chance of reading a document written on another
computer, another word processor, or another network. -- Tim Berners-Lee

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.php

csiph-web