Doc #71927 [Com]: string interpolation with ${}
Edit report at https://bugs.php.net/bug.php?id=71927&edit=1
ID: 71927
Comment by: autoupdatedaily at gmail dot com
Reported by: 1783946138 at qq dot com
Summary: string interpolation with ${}
Status: Open
Type: Documentation Problem
Package: Scripting Engine problem
PHP Version: 7.0.5
Block user comment: N
Private report: N
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Previous Comments:
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[2016-03-31 06:39:36] requinix@php.net
Huh. https://3v4l.org/jQXFc
I think this is intentional. Or at least a side-effect of intentional design.
${expression} basically has two behaviors:
1. If "expression" is a valid variable name then the value of $expression (or empty string
if not defined) is interpolated into the string.
2. If "expression" is not a valid variable name then expression is evaluated and the
result is expected to be the name of a variable which can be interpolated.
The first three variations are not valid variable names so the expressions "great ",
" great", and " great " are evaluated using the constant and the result is
effectively ${my} = "my value".
The fourth variation is a valid variable name and so is interpolated as $great =
"fantastic".
This is a little different from how the same syntax works outside of strings: the
"expression" is *always* treated as an expression. https://3v4l.org/IjhcH
http://php.net/manual/en/language.types.string.php#language.types.string.parsing.complex
I feel like that section could go into more detail about how the {$} and ${} syntaxes work and about
what all is and is not allowed with each.
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[2016-03-31 01:27:52] 1783946138 at qq dot com
Description:
------------
The unstable result to use "{}" in string interpolation.It's just because useing
space.
Test script:
---------------
error_reporting(E_ALL);
define('great','my');
$great='fantastic';
$my='my value';
echo "This is ${great }<br/>";//output:my value
echo "This is ${ great}<br/>";//output:my value
echo "This is ${ great }<br/>";//output:my value
echo "This is ${great}<br/>";//output:fantastic
Expected result:
----------------
none
Actual result:
--------------
none
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Edit this bug report at https://bugs.php.net/bug.php?id=71927&edit=1
Thread (3 messages)