Floating point precision in PHP

Answer:

It is typical that simple decimal fractions like 0.1 or 0.7 cannot be converted into their internal binary counterparts without a small loss of precision. This can lead to confusing results: for example, floor((0.1+0.7)*10) will usually return 7 instead of the expected 8, since the internal representation will be something like 7.9.

E.g.

$a = 0.1;
$b = 0.7;

print $a + $b;
print (( $a + $b ) * 10);

Reference: http://www.php.net/manual/en/language.types.float.php

So, never compare two floating numbers in your program.

Faster string length testing in PHP

Answer:

If you want to ensure a string variable has a particular length, you might use strlen

if ( strlen($str) > 10 ) {
    // ...
}

A faster approach is to use isset

if ( isset($str[10]) ) {
    // ...
}