Floating point numbers

Floating point numbers (AKA "floats", "doubles" or "real numbers") can be specified using any of the following syntaxes:

<?php $a = 1.234; $b = 1.2e3; $c = 7E-10;?>

Formally:

LNUM          [0-9]+ DNUM          ([0-9]*[\.]{LNUM}) | ({LNUM}[\.][0-9]*) EXPONENT_DNUM ( ({LNUM} | {DNUM}) [eE][+-]? {LNUM})

The size of a float is platform-dependent, although a maximum of ~1.8e308 with a precision of roughly 14 decimal digits is a common value (that's 64 bit IEEE format).