文字列の長さを得る mb_strlen

mb_strlen ( string $string , string|null $encoding = null ) : int

<?php

//マルチバイト文字列の長さを取得します。
//10個
$str = "犬も歩けば棒に当たる";

$len = mb_strlen($str);
echo "1.".$len.PHP_EOL;

//45個
$str = "Peter Piper picked a peck of pickled peppers.";

$len = mb_strlen($str);
echo "2.".$len.PHP_EOL;

//空白なし 10個
$str = "PeterPiper";

$len = mb_strlen($str);
echo "3.".$len.PHP_EOL;

//半角空白 11個
$str = "Peter Piper";

$len = mb_strlen($str);
echo "4.".$len.PHP_EOL;

//全角空白 11個
$str = "Peter　Piper";

$len = mb_strlen($str);
echo "5.".$len.PHP_EOL;