入力した波ダッシュが全角チルダに化けるまたはその逆について

wave-or-tilde.php

<?php
$wave = "\u{301C}";
$tilde = "\u{FF5E}";

// EUC-JP has no different character for wavy dash and full width tilde
$eucWave = mb_convert_encoding($wave, 'euc-jp', 'utf-8');
$eucTilde = mb_convert_encoding($tilde, 'euc-jp', 'utf-8');
assert($eucWave == $eucTilde);

// euc-jp to utf-8: always wavey dash
$revertedEucWave = mb_convert_encoding($eucWave, 'utf-8', 'euc-jp');
$revertedEucTilde = mb_convert_encoding($eucTilde, 'utf-8', 'euc-jp');
assert($revertedEucWave == $wave);
assert($revertedEucTilde == $wave);

// eucJP-win to utf-8: always full width tilde
$revertedEucWinWave = mb_convert_encoding($eucWave, 'utf-8', 'eucJP-win');
$revertedEucWinTilde = mb_convert_encoding($eucTilde, 'utf-8', 'eucJP-win');
assert($revertedEucWinWave == $tilde);
assert($revertedEucWinTilde == $tilde);