PHP マニュアル: Round down arbitrary precision number

string bcfloor(string $num)

Returns the next lowest integer value by rounding down num if necessary.

Returns a numeric string representing num rounded down to the nearest integer.

This function throws a ValueError if num is not a well-formed BCMath numeric string.

例1 bcfloor example

<?php
var_dump(bcfloor('4.3'));
var_dump(bcfloor('9.999'));
var_dump(bcfloor('-3.14'));
?>

上の例の出力は以下となります。

string(1) "4"
string(1) "9"
string(2) "-4"