PHPで値を整数に変換する方法

<?php
$str = &#39;123.456abc&#39;;
$int = (int)$str;
echo $int."<br>";

$float = 3.14;
$int = (integer)$float;
echo $int."<br>";
?>

<?php
$str = &#39;123.456abc&#39;;
$int = intval($str);
echo $int."<br>";

$float = 5.64;
$int = intval($float);
echo $int."<br>";

$bool = true;
$int = intval($bool);
echo $int."<br>";
?>

<?php
header("Content-type:text/html;charset=utf-8"); 
$num = 123.456;
$int = ceil($num);
echo &#39;变量 $int 的类型为：&#39;.gettype($int).&#39;<br>&#39;;
echo $int;
?>

<?php
header("Content-type:text/html;charset=utf-8"); 
$num = 123.456;
$int = floor($num);
echo &#39;变量 $int 的类型为：&#39;.gettype($int).&#39;<br>&#39;;
echo $int;
?>