Problem
You want to include the results of executing a function or expression within a string.
Solution
Use the string concatenation operator (.), as shown in Example 1-27, when the value you want to include can’t be inside the string.
Example 1-27. String concatenation
[sourcecode language=”php”]
<?php
print ‘You have ‘.($_REQUEST[‘boys’] + $_REQUEST[‘girls’]).’ children.’;
print "The word ‘$word’ is ".strlen($word).’ characters long.’;
print ‘You owe ‘.$amounts[‘payment’].’ immediately’;
print "My circle’s diameter is ".$circle->getDiameter().’ inches.’;
?>
[/sourcecode]
Discussion
You can put variables, object properties, and array elements (if the subscript is unquoted) directly in double-quoted strings:
[sourcecode language=”php”]
<?php
print "I have $children children.";
print "You owe $amounts[payment] immediately.";
print "My circle’s diameter is $circle->diameter inches.";
?>
[/sourcecode]
Interpolation with double-quoted strings places some limitations on the syntax of what can be interpolated. In the previous example, $amounts[‘payment’] had to be written as $amounts[payment] so it would be interpolated properly. Use curly braces around more complicated expressions to interpolate them into a string. For example:
[sourcecode language=”php”]
<?php
print "I have less than {$children} children.";
print "You owe {$amounts[‘payment’]} immediately.";
print "My circle’s diameter is {$circle->getDiameter()} inches.";
?>
[/sourcecode]
Direct interpolation or using string concatenation also works with heredocs. Interpolating with string concatenation in heredocs can look a little strange because the closing heredoc delimiter and the string concatenation operator have to be on separate lines:
[sourcecode language=”php”]
<?php
print <<< END
Right now, the time is
END
. strftime(‘%c’) . <<< END
but tomorrow it will be
END
. strftime(‘%c’,time() + 86400);
?>
[/sourcecode]
Also, if you’re interpolating with heredocs, make sure to include appropriate spacing for the whole string to appear properly. In the previous example, Right now the time has to include a trailing space, and but tomorrow it will be has to include leading and trailing spaces.
See Also
For the syntax to interpolate variable variables (such as ${“amount_$i”}), see Recipe 5.4; documentation on the string concatenation operator at http://www.php.net/language.operators.string.