PHP String Interpolation Syntax

String interpolation for built-in functions

You could do it like so:

$foo = 'bar';

$func = "strtoupper";
echo "test: {$func($foo)}";
//or for assignments:
$path = sprintf(
    '%s/%s',
    $dir,
    basename($file)
); 

example here

But really, you shouldn't: it obfuscates what you're actually doing, and makes a trivial task look a lot more complex than it really is (debugging and maintaining this kind of code is a nightmare).

I personally prefer to keep the concatenation, or -if you want- use printf here:

printf(
    'Test: %s',
    strtoupper($foo)
);

Php string interpolation

The string interpolation rules are described thoroughly in the PHP manual. Importantly, there are two main styles:

• One with plain variables in the string, like "the $adjective apple", which also supports some expressions like $foo->bar in "the $foo->bar apple"
• One with curly brackets, which supports more complex expressions, like {$foo->bar()}, but the expression must start with a $

When PHP sees your string:

• it first sees {count(, but because the character after { isn't $, it doesn't mean anything special
• it then sees the $this->movies, which is valid for the first syntax, so it tries to output $this->movies as a string
• because $this->movies is an array, you get a Warning and the string "Array" is used

The result is that the string will always say "Your collection exists of {count(Array} movies.".

---

There is no interpolation syntax currently that supports function calls like count(), so you'll have to use concatenation or an intermediate variable:

return "Your collection exists of " . count($this->movies) . " movies.";

or

$movieCount = count($this->movies);
return "Your collection exists of {$movieCount} movies.";

or

$movieCount = count($this->movies);
return "Your collection exists of $movieCount movies.";

How can I manually interpolate a string?

Here is a possible solution. I am not sure in your particular scenario if this would work for you, but it would definitely cut out the need for so many single and double quotes.

<?php
    class a {
        function b() {
            return "World";
        }
    }
    $c = new a;
    echo eval('Hello {$c->b()}.');
?>

How do I use PHP string interpolation and square brackets in a MySQL regexp?

Add braces: $search .= "and title REGEXP '[[:<:]]{$q}[[:>:]]'"; -- otherwise it thinks you are referencing the $q array.

PHP allows array lookups in strings, such as "... $q[...] ..." It also allows expresssions: "... {$a+$b} ..." if you add the braces. Putting those together solves this problem.

Constants inside quotes are not printed?

Because "constants inside quotes are not printed". The correct form is:

echo "This is a constant: " . CONSTANT;

The dot is the concatenation operator.

What is the difference between these PHP string interpolation syntaxes

The first one is interpolation plus variable variable (dynamic variable), meaning you can use expressions here to define the name of the variable you want to interpolate "${func()}" While the second one syntax is used to distinct variable from the text "some{$variable}text". You can actually combine them:

function func(){
    return 'foo';
}
$foo = 'bar';
echo "some{${func()}}text";

Outputs: somebartext

PHP: Interpolating a PHP variable in a string block

Yes, it's called heredoc syntax:

$str = <<<EOD
Example of string
spanning multiple lines
using heredoc syntax.
EOD;

http://www.php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc

---

Related Topics