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Re: When do I use {}? [message #169557 is a reply to message #169530]

Fri, 17 September 2010 19:37

Chuck Anderson
Messages: 63
Registered: September 2010

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Jerry Stuckle wrote:
> On 9/16/2010 10:13 PM, bruceaj wrote:
>
>> I have code samples where some variables are wrapped in {} (curly
>> brackets.) My problem is that I can find anything in the documentation
>> when they can be uses.
>>
>> Can someone tell me or point me to some documentation??
>>
>> Thanks...
>>
>> Bruce
>>
>
> You use them when you want to evaluate non-simple variables (i.e. array
> elements) in a double-quoted string, such as:
>
> $a = 'World"; // init variable
> $b = array('Hello', 'World');
>
> echo "Hello $a"; // Works - $a is a simple variable
> echo "Hello {$a}"; // Also works - and may be clearer
>
> echo "Hello $b[1]"; // Does NOT work - $b is an array
> echo "Hello {$b[1]}"; // This one works
> echo "{$b[0]} {$b[1]}"; // Also works
>
>

Actually ....
echo "Hello $b[1]"; // DOES work - $b[1] is not an array

You need them when you want to evaluate *associative* array elements
within a double-quoted string, such as:
$b = array('first' => 'Hello', 'second' => 'World');

Then ...
echo "Hello $b['second']"; // does NOT work - syntax error
echo "Hello {$b['second']}"; // DOES work

And as a side note ...
echo "Hello $b[first]";
.... also works. Constants are not evaluated when within double quoted
strings.
See
http://www.php.net/manual/en/language.types.array.php#language.types.array. foo-bar
(read "More examples ...").

Curly brackets are also required when a valid variable name character
follows a variable within a string.
$a = 'underscore';
echo "I like to use $as" instead of spaces"; // does NOT work
// $as is undefined
echo "I like to use $a's" instead of spaces"; // DOES work
// ' is not a valid variable name character
echo "I like to use {$a}s" instead of spaces"; // DOES work
// {$a} is evaluated separate from the s

--
*****************************
Chuck Anderson • Boulder, CO
http://www.cycletourist.com
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[Message index]

		When do I use {}? By: bruceaj on Fri, 17 September 2010 02:13
		Re: When do I use {}? By: Marious Barrier on Fri, 17 September 2010 02:57
		Re: When do I use {}? By: The Natural Philosoph on Fri, 17 September 2010 09:28
		Re: When do I use {}? By: Erwin Moller on Fri, 17 September 2010 09:36
		Re: When do I use {}? By: Jerry Stuckle on Fri, 17 September 2010 11:29
		Re: When do I use {}? By: Captain Paralytic on Fri, 17 September 2010 09:53
		Re: When do I use {}? By: Marious Barrier on Fri, 17 September 2010 16:40
		Re: When do I use {}? By: Denis McMahon on Fri, 17 September 2010 13:31
		Re: When do I use {}? By: Marious Barrier on Fri, 17 September 2010 16:39
		Re: When do I use {}? By: Jerry Stuckle on Fri, 17 September 2010 03:47
		Re: When do I use {}? By: bruceaj on Fri, 17 September 2010 17:44
		Re: When do I use {}? By: matt[1] on Fri, 17 September 2010 18:06
		Re: When do I use {}? By: Michael Fesser on Fri, 17 September 2010 20:51
		Re: When do I use {}? By: Chuck Anderson on Fri, 17 September 2010 19:37
		Re: When do I use {}? By: Michael Fesser on Fri, 17 September 2010 13:13
		Re: When do I use {}? By: bruceaj on Fri, 17 September 2010 17:48

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