This question already has an answer here:
What is the difference between the two following methods (performance, readability, etc.) and what do you prefer?
echo "Welcome {$name}s!"
vs.
echo "Welcome ".$name."!";
Whatever works best for you works... But if you want to go for speed use this:
echo 'Welcome ', $name, '!';
The single quotes tell PHP that no interpretation is needed, and the comma tells PHP to just echo the string, no concatenation needed.
来源:https://stackoverflow.com/questions/16790501/php-variable-interpolation-vs-concatenation