PHP’s echo statement can be used with commas separating the elements to be output, or with dots. So either:
echo $a, $b, $c;
/* or */
echo $a . $b . $c;
I’ve usually preferred to use commas, because I figured that using a dot would cause PHP first to concatenate the items into a single string, and then output that. Seems like it would take longer, you’d think.
I’ve just seen a post at https://electrictoolbox.com/php-echo-commas-vs-concatenation/, apparently showing that I was right, and that using dots is slower than commas.
Thing is, this was posted many years ago, and I’m not sure what version of PHP the author was using.
I’ve just repeated the tests using the example code in that post, and on my local server running PHP 7.3, the results are different, and if anything, using dots is now quicker than using commas.
Using dots – elapsed time for the test was generally around 2.1 seconds
Using commas – elapsed time was pretty much always 2.3 seconds.
Now, for four million echos, that’s a negligible difference. I think I’ll stick with commas.