#! /usr/local/bin/php
PHP_INT_MAX
echo:           9223372036854775807
echo float:     9.2233720368548E+18
echo int float: -9223372036854775808
printf:         9223372036854775808.000000

PHP_INT_MAX - 1
echo:           9223372036854775806
echo float:     9.2233720368548E+18
echo int float: -9223372036854775808
printf:         9223372036854775808.000000

(PHP_INT_MAX - 1) / 2
echo:           4611686018427387903
echo float:     4.6116860184274E+18
echo int float: 4611686018427387904
printf:         4611686018427387904.000000