underlying difference between elseif vs else if

Question

I was wondering the differnce between elseif and else if.

I was reading the manual which says if using the braces {} they are

Answer 1

The "speed difference" in that comment is not statistically significant. Aside from else if: not parsing, there's no effective difference.

Answer 2

Regarding the efficiency, and based on what I have been studying for a long time. There is no difference.

Answer 3

In addition to my comment, from what I can see in the PHP source, the only speed boost is that PHP's parser has a special token for elseif, unsurprisingly known as T_ELSEIF. But I'm sure the speed boost is nothing more than a side effect of allowing elseif in the alternative syntax:

if (cond1):
    // Do something
elseif (cond2):
    // Do something else
else:
    // Do something else
endif;

Similar to Python, which uses elif, else if with a space wouldn't be allowed without having to unnecessarily complicate the parser's implementation code (i.e. to act differently between seeing a colon and the if keyword). So a colon is required directly after else and if respectively, and that's how the language rule is stipulated.

Ergo I'm pretty sure PHP just treats else if as a conditional block in a singular-statement else.

If there are any speed differences at all, blame the parser for most of them.

Answer 4

In Manual I read out(See Note):

Note: Note that elseif and else if will only be considered exactly the same when using curly brackets as in the above example. When using a colon to define your if/elseif conditions, you must not separate else if into two words, or PHP will fail with a parse error.

Example:

<?php

/* Incorrect Method: */
if($a > $b):
    echo $a." is greater than ".$b;
else if($a == $b): // Will not compile.
    echo "The above line causes a parse error.";
endif;


/* Correct Method: */
if($a > $b):
    echo $a." is greater than ".$b;
elseif($a == $b): // Note the combination of the words.
    echo $a." equals ".$b;
else:
    echo $a." is neither greater than or equal to ".$b;
endif;

?>