I noticed today when I was using mysql_fetch_array something weird happened.

Database:
| id |
1

Code:
$colVal = "id";
$foo=mysql_fetch_array($someresult, MYSQL_***OC);

Now all I wanted to do was get the value of 1 into the variable $bar. Please
***ume $someresult was the direct product of mysql_query("select * from
thistable");.

$bar = $foo['$colVal']; // didn't work
$bar = $foo['{$colVal}']; // didn't work
$bar = $foo[$colVal]; // worked
$bar = $foo['id']; // obviously worked

What I don't understand is why the first or second option didn't work.

Can anybody shed some light on this?

Brian Seymour
AeroCoreProductions
http://www.aerocore.net/

On 6/2/07, Brian Seymour <EMAIL REMOVED> wrote:
> I noticed today when I was using mysql_fetch_array something weird happened.
>
> Database:
> | id |
> 1
>
> Code:
> $colVal = "id";
> $foo=mysql_fetch_array($someresult, MYSQL_***OC);
>
> Now all I wanted to do was get the value of 1 into the variable $bar. Please
> ***ume $someresult was the direct product of mysql_query("select * from
> thistable");.
>
> $bar = $foo['$colVal']; // didn't work
> $bar = $foo['{$colVal}']; // didn't work
> $bar = $foo[$colVal]; // worked
> $bar = $foo['id']; // obviously worked
>
> What I don't understand is why the first or second option didn't work.
>
> Can anybody shed some light on this?
>
> Brian Seymour
> AeroCoreProductions
> http://www.aerocore.net/
>
> --
> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>

Brian,

Single quotes give a literal value of the data p***ed, while
double quotes give the translated value. For example, if you have the
following:
<?
$the = "end";

echo '$the';

echo " ";

echo "$the";
?>

.... you'll have the following output:
$the end

The same counts for escaped characters, such as the newline
character (\n). If you put it in single quotes, it's processed as a
literal value; the same newline inserted in double quotes is displayed
properly, as again, it's processed as a translated value.

So:
<?
$word = "this";

echo '$word\nworks';

echo "\n\n";

echo "$word\nworks";
?>

Shows:
$word\nworks

this
works


Hope that helps a bit. I'm in the middle of moving furniture into
my new house and can't get the bed upstairs, so I decided to take a
break and grab some "sanity" from the list. Talk about your
oxymorons....


--
Daniel P. Brown
[office] (570-) 587-7080 Ext. 272
[mobile] (570-) 766-8107

On Sat, June 2, 2007 3:15 pm, Brian Seymour wrote:
> $bar = $foo['$colVal']; // didn't work
> $bar = $foo['{$colVal}']; // didn't work
> $bar = $foo[$colVal]; // worked
> $bar = $foo['id']; // obviously worked
>
> What I don't understand is why the first or second option didn't work.
>
> Can anybody shed some light on this?

' is actually easier to explain.

' has only TWO special characters you can embed in it: ' and \

$foo = 'That\'s life!';
$bar = 'The backslash \\ should be escaped, because it\'s special';

You don't HAVE to escape \ with \\ if PHP won't get "confused" by
whatever else you have in your string, but it's a Good Idea, imho, to
just always escape it, so you understand what the string parser is
doing internally.

" is a bit more complex.

In addition to " and \ being special, exactly parallel to ' and \
inside '', you also have:
variables like $foo and 1-D arrays like $foo[id]
special control characters like \n \t \r
any char you want with octal
{ and } for some versions (ugh) of PHP

There is also heredoc syntax, which is probably best for large chunks
of text, in general.

Full documentation is here:
http://us.php.net/manual/en/language.types.string.php

--
Some people have a "gift" link here.
Know what I want?
I want you to buy a CD from some indie artist.
http://cdbaby.com/browse/from/lynch
Yeah, I get a buck. So?