Hey all, I was playing around this morning with a little test to decide
whether string substitution is faster or slower than concatenation. I
figured that, since printing variable values is one of the most common
actions in a script finding which method is best would be important.
I've been suspecting that string substitution was slower and have tried
not to use it as a general rule of thumbs.
I found it sort-of interesting that--at least according to my
test--string substitution is significantly slower than concatenation by
quite a bit (like 40%).
Here's my script--let me know if you find any flaws that skew the
results:
<?
$num_tries = 500000;
function print_microtime($t)
{
$t = explode (' ', $t);
return number_format ($t[1]+$t[0], 10);
}
function print_microtime_diff($t1, $t2, &$res)
{
$t1 = explode (' ', $t1);
$t2 = explode (' ', $t2);
$res = ($t2[1] + $t2[0]) - ($t1[1] + $t1[0]);
return number_format ($res, 10);
}
$start = microtime();
$s = 'test string';
for ($i = 0; $i < $num_tries; $i++)
$a = 'test ' . $s . ' string';
$end = microtime();
echo "Normal concatenation\n";
echo 'Start: ' . print_microtime($start) . "\n";
echo 'End: ' . print_microtime($end) . "\n";
echo 'Diff: ' . print_microtime_diff ($start, $end, $diff1) . "\n\n";
$start = microtime();
$s = 'test string';
for ($i = 0; $i < $num_tries; $i++)
$a = "test $s string";
$end = microtime();
echo "String substitution\n";
echo 'Start: ' . print_microtime($start) . "\n";
echo 'End: ' . print_microtime($end) . "\n";
echo 'Diff: ' . print_microtime_diff ($start, $end, $diff2) . "\n\n";
echo 'Difference in timing: ' . ($diff2 - $diff1) . ' (' . number_format
(($diff2 - $diff1) / $diff1 * 100, 2) . "%)\n\n";
?>
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