Which way to write this code is most the efficient?

Question

If I am inside a ton of PHP code, instead of coming out of PHP I usually write code which contains variables like so:

echo "This is how I use a ".$variable." inside a string";

but is it more efficient to actually get out of PHP like so:

?>

Should I instead use the <? echo $variable; ?> like this

<? // then back into PHP

Throughout a page there will be lots of instances of code like this as I fill pages with dynamic content, or is this too much of a generalisation?

Answer 1

I only suggest breaking out of php tags when echoing HTML, not just a string.

This is fine for just a string:

// You don't need to concat, double quotes interpolate variables
echo "This is how I use a $variable inside a string";

But with HTML, personally, I like to do this:

<?php //... ?>
<div>
    <span>This is how I use a <?=$variable?> inside HTML</span>
</div>
<?php //... ?>

Answer 2

Using echo appears to be slightly faster. I made this simple benchmark script:

<?php
$variable = "hello world";
$num = 10000;
$start1 = microtime(true);
for ($i = 0; $i<$num;$i++) {    
    echo "test " . $variable . " test\n";    
}
$time1 = microtime(true) - $start1;
$start2 = microtime(true);
for ($i = 0; $i<$num;$i++) {
    ?>test <?php echo $variable;?> test
<?
}
$time2 = microtime(true) - $start2;
echo "\n$time1\n$time2\n";

The echo loop was consistently about 25% faster.

In reality this difference is so minor it wouldn't have any impact on overall performance unless you were literally doing millions of such output statements. I would still recommend using echo just because it's more straightforward and easier to read.