A number of comments on this page have missed the fundamental point that the question is ill-formed. Floating point is a binary representation, designed for efficient calculations; it fundamentally has no notion of decimal digits of any sort.
So asking this:
How do I get "0.00" instead of "0" and still have the data type as a float?
Is like asking this:
How do I get "deux" instead of "zwei" and still have the language as English?
Whether you specify the input as "2", or "2.0", or "2.000000000", if you ask for a floating point value, what will be stored in memory is this (in IEEE 754 double-precision):
0100000000000000000000000000000000000000000000000000000000000000
If you convert to an integer, the value stored in memory is this (assuming a 64-bit system):
0000000000000000000000000000000000000000000000000000000000000010
(Note that "integer" in this context is not just a synonym for "whole number", it is a specific data type, with its own rules for how values should be represented in memory.)
By contrast, the string "2" would look like this:
00110010
And the string "2.00" would look like this:
00110010001011100011000000110000
(In a PHP program, there would actually be additional information in memory, such as an indicator of the type, but that's not really relevant here.)
So, the question can only be answered by rephrasing it as a conversion: given the input of a floating point number, how do I choose a string representation which has a fixed number of decimals.
As others have pointed out, the answer to that is to use number_format.
The question doesn't mention JSON, but several comments do, so I will also point out that PHP's json_encode function has an option JSON_PRESERVE_ZERO_FRACTION, which will format a floating point number that happens to be a whole number with a trailing ".0", for instance:
$example = ['int' => 2, 'float' => 2.0]; echo json_encode($example); # => {"int":2,"float":2} echo json_encode($example, JSON_PRESERVE_ZERO_FRACTION); # => {"int":2,"float":2.0}Again, note that this is a string representation of the value.