PHP echo vs PHP short echo tags

<? and <?= are called short open tags, and are not always enabled (see the short_open_tag directive) with PHP 5.3 or below (but since PHP 5.4.0, <?= is always available).

Actually, in the php.ini-production file provided with PHP 5.3.0, they are disabled by default:

$ grep 'short_open' php.ini-production; short_open_tagshort_open_tag = Off

So, using them in an application you want to distribute might not be a good idea: your application will not work if they are not enabled.

<?php, on the other side, cannot be disabled -- so, it's safest to use this one, even if it is longer to write.

Except the fact that short open tags are not necessarily enabled, I don't think there is much of a difference.

Echo is generally just better to use because...

1. It supports good programming style.
2. It can't be turned off in php.ini (short tags can be)
3. Short tags will be removed in PHP 6)

But, they are generally the same. See also:

1. Are PHP short tags acceptable to use?
2. How are echo and print different in PHP?

http://php.net/manual/en/language.basic-syntax.phpmode.php states:

Starting with PHP 5.4, short echo tag is always recognized and valid, regardless of the short_open_tag setting.

short_open_tag Off or On doesn't matter anymore.

So now you can, without concern, put tags like this in your templates:

    <?= (($test) ? "val1" : "val2") ?>

It is official now, the "short echo tag" is something very different than the "short tag".