Never had to do such a basic thing before. How do I initialize a variable as a float before doing logic? Do either of these examples make sense?
$var = 0.0;
$var = (float) 0;
Both make sense, the first is shorter, with the second you can initialized with a dynamic value, your choice !
EDIT : But I agree with @Niet the Dark Absol, it poorly matters since you use test function such as ctype_digit, or is_numeric.
Try to use number_format.
For example:
$number = 20;
echo number_format($number,2) // will output 20.00
// number_format($number,$decimals,$dec_point,$thousands_sep)
from http://php.net/manual/en/language.types.float.php
Floating point numbers (also known as "floats", "doubles", or "real numbers") can be specified using any of the following syntaxes:
<?php $a = 1.234; $b = 1.2e3; $c = 7E-10; ?>
so defining a float by using $var = 0.0 is correct. While casting is not technically incorrect I don't believe it's something you should use when you don't need to.