str_rot13

例

文字列のエンコードとデコード：

 <span class="token php language-php"><span class="token delimiter important"><？php</span>
<span class="token keyword">echo</span> <span class="token function">str_rot13</span> <span class="token punctuation">（</span> <span class="token string double-quoted-string">"I Love Shanghai"</span> <span class="token punctuation">）</span> <span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token function">str_rot13</span> <span class="token punctuation">（</span> <span class="token string double-quoted-string">"v ybir funatunv"</span> <span class="token punctuation">）</span> <span class="token punctuation">;</span>
<span class="token delimiter important">？></span></span>

自分で試してみてください