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Is there a performance benefit single quote vs double quote in php?
I am wondering if PHP code takes a performance hit when using "s when defining strings containing no variables, compared to ' where the extra parsing is not performed.
For example, PHP will try to parse variables inside strings defined by " but not '.
$myString = "Greetings earthlings!";
echo '$myString'; //literally outputs the string '$myString'
echo "$myString"; //literally outputs the string "Greetings earthlings"
So my question is, all this time I've been writing code like this:
echo "Greetings earthlings";
Have I been wasting cycles? Or is PHP smart/optimized enough to know I really meant:
echo 'Greetings earthlings';
?
A bit of work with VLD tells me that both programs compile to identical bytecode (using PHP 5.3):
line # * op fetch ext return operands
---------------------------------------------------------------------------------
2 0 > ECHO 'Hello+world'
3 1 > RETURN 1
Conclusion: There's absolutely no difference in modern versions of PHP. None whatsoever. Use whatever feels best to you.
There is, however, a difference between echo "Hello $world":
compiled vars: !0 = $world
line # * op fetch ext return operands
---------------------------------------------------------------------------------
1 0 > ADD_STRING ~0 'Hello+'
1 ADD_VAR ~0 ~0, !0
2 ECHO ~0
3 > RETURN null
And echo "Hello " . $world:
compiled vars: !0 = $world
line # * op fetch ext return operands
---------------------------------------------------------------------------------
1 0 > CONCAT ~0 'Hello+', !0
1 ECHO ~0
2 > RETURN null
I'd hesitate to call that significant, though. The actual real-world difference in performance is, in all probability, trivial.