Retaining Value of a Ceil-ed Function

[aquastream]

Okay, here's a newbie theoretical question. In other words, something I've come across which I have no idea why I would ever use but I'm curious about it anyway!

 

If i add a number to a variable, the answer to this becomes the new value of that variable, and if I subtracted a number from the variable, it would then subtract it from the new value rather than the original value.

 

For example:

 

<?php

$variable1 = 2;

$variable1 += 4; echo $variable1."<br />";

$variable1 -= 1; echo $variable1;

?>

 

However, when I use either a ceil or floor function to a float, the rounded value doesn't behave like the previous example. Instead, when I do a mathematical function to the variable, it takes it from the original value rather than the new ceil-ed or floor-ed value.

 

For example:

 

<?php

$variable1 = 3.14;

echo ceil($variable1)."<br />";

$variable1 += 1; echo $variable1

?>

 

Is the reason for this something to do with the fact that ceil and floor aren't pure mathematical functions like adding or squaring? If I wanted to in the previous example retain the value of the ceil (4) when adding to its value, how would I do this?

 

PS: Brownie points to anyone who can come up with a reason as to why I would do this in a real project.

[jl5501]

ceil etc are functions which output their results. The input could be a single variable or a whole expression.

 

So if you need to do other than echo the output, you need to store it in a variable.

 

$a = ceil($b);

[aquastream]

Thanks jl5501. That's so simple I probably should have thought of it, but I didn't and that's why I'm glad communities like this exist.