Detailed explanation of how PHP converts full-width symbols in text to half-width

PHP如何将文本中的全角符号转为半角？本文将分享一个封装好的转换方法，大家可以参考一下。希望对大家有所帮助。

将一个字串中含有全角的数字字符、字母、空格或'%+-()'字符转换为相应半角字符

/** 
* 将一个字串中含有全角的数字字符、字母、空格或'%+-()'字符转换为相应半角字符 
* @access public 
* @param string $str 待转换字串 
* @return string $str 处理后字串 
*/ 
function make_semiangle($str) 
{ 
    $arr = array(&#39;０&#39; => &#39;0&#39;, &#39;１&#39; => &#39;1&#39;, &#39;２&#39; => &#39;2&#39;, &#39;３&#39; => &#39;3&#39;, &#39;４&#39; => &#39;4&#39;,&#39;５&#39; => &#39;5&#39;, &#39;６&#39; => &#39;6&#39;, &#39;７&#39; => &#39;7&#39;, &#39;８&#39; => &#39;8&#39;, &#39;９&#39; => &#39;9&#39;, &#39;Ａ&#39; => &#39;A&#39;, &#39;Ｂ&#39; => &#39;B&#39;, &#39;Ｃ&#39; => &#39;C&#39;, &#39;Ｄ&#39; => &#39;D&#39;, &#39;Ｅ&#39; => &#39;E&#39;,&#39;Ｆ&#39; => &#39;F&#39;, &#39;Ｇ&#39; => &#39;G&#39;, &#39;Ｈ&#39; => &#39;H&#39;, &#39;Ｉ&#39; => &#39;I&#39;, &#39;Ｊ&#39; => &#39;J&#39;, &#39;Ｋ&#39; => &#39;K&#39;, &#39;Ｌ&#39; => &#39;L&#39;, &#39;Ｍ&#39; => &#39;M&#39;, &#39;Ｎ&#39; => &#39;N&#39;, &#39;Ｏ&#39; => &#39;O&#39;,&#39;Ｐ&#39; => &#39;P&#39;, &#39;Ｑ&#39; => &#39;Q&#39;, &#39;Ｒ&#39; => &#39;R&#39;, &#39;Ｓ&#39; => &#39;S&#39;, &#39;Ｔ&#39; => &#39;T&#39;,Ｕ&#39; => &#39;U&#39;, &#39;Ｖ&#39; => &#39;V&#39;, &#39;Ｗ&#39; => &#39;W&#39;, &#39;Ｘ&#39; => &#39;X&#39;, &#39;Ｙ&#39; => &#39;Y&#39;,&#39;Ｚ&#39; => &#39;Z&#39;, &#39;ａ&#39; => &#39;a&#39;, &#39;ｂ&#39; => &#39;b&#39;, &#39;ｃ&#39; => &#39;c&#39;, &#39;ｄ&#39; => &#39;d&#39;,&#39;ｅ&#39; => &#39;e&#39;, &#39;ｆ&#39; => &#39;f&#39;, &#39;ｇ&#39; => &#39;g&#39;, &#39;ｈ&#39; => &#39;h&#39;, &#39;ｉ&#39; => &#39;i&#39;,&#39;ｊ&#39; => &#39;j&#39;, &#39;ｋ&#39; => &#39;k&#39;, &#39;ｌ&#39; => &#39;l&#39;, &#39;ｍ&#39; => &#39;m&#39;, &#39;ｎ&#39; => &#39;n&#39;,&#39;ｏ&#39; => &#39;o&#39;, &#39;ｐ&#39; => &#39;p&#39;, &#39;ｑ&#39; => &#39;q&#39;, &#39;ｒ&#39; => &#39;r&#39;, &#39;ｓ&#39; => &#39;s&#39;, &#39;ｔ&#39; => &#39;t&#39;, &#39;ｕ&#39; => &#39;u&#39;, &#39;ｖ&#39; => &#39;v&#39;, &#39;ｗ&#39; => &#39;w&#39;, &#39;ｘ&#39; => &#39;x&#39;, &#39;ｙ&#39; => &#39;y&#39;, &#39;ｚ&#39; => &#39;z&#39;,&#39;（&#39; => &#39;(&#39;, &#39;）&#39; => &#39;)&#39;, &#39;〔&#39; => &#39;[&#39;, &#39;〕&#39; => &#39;]&#39;, &#39;【&#39; => &#39;[&#39;,&#39;】&#39; => &#39;]&#39;, &#39;〖&#39; => &#39;[&#39;, &#39;〗&#39; => &#39;]&#39;, &#39;“&#39; => &#39;[&#39;, &#39;”&#39; => &#39;]&#39;,&#39;‘&#39; => &#39;[&#39;, &#39;&#39;&#39; => &#39;]&#39;, &#39;｛&#39; => &#39;{&#39;, &#39;｝&#39; => &#39;}&#39;, &#39;《&#39; => &#39;<&#39;,&#39;》&#39; => &#39;>&#39;,&#39;％&#39; => &#39;%&#39;, &#39;＋&#39; => &#39;+&#39;, &#39;—&#39; => &#39;-&#39;, &#39;－&#39; => &#39;-&#39;, &#39;～&#39; => &#39;-&#39;,&#39;：&#39; => &#39;:&#39;, &#39;。&#39; => &#39;.&#39;, &#39;、&#39; => &#39;,&#39;, &#39;，&#39; => &#39;.&#39;, &#39;、&#39; => &#39;.&#39;, &#39;；&#39; => &#39;,&#39;, &#39;？&#39; => &#39;?&#39;, &#39;！&#39; => &#39;!&#39;, &#39;…&#39; => &#39;-&#39;, &#39;‖&#39; => &#39;|&#39;, &#39;”&#39; => &#39;"&#39;, &#39;&#39;&#39; => &#39;`&#39;, &#39;‘&#39; => &#39;`&#39;, &#39;｜&#39; => &#39;|&#39;, &#39;〃&#39; => &#39;"&#39;,&#39;　&#39; => &#39; &#39;); 
    return strtr($str, $arr); 
}

<?php 
    $str = "０１２３ＡＢＣＤＦＷＳ＼＂，．？＜＞｛｝［］＊＆＾％＃＠！～（）＋－｜：；"; 
    echo "$str"; 
    echo "<br />"; 
    $str = preg_replace(&#39;/\xa3([\xa1-\xfe])/e&#39;, &#39;chr(ord(\1)-0x80)&#39;, $str); 
    echo $str; 
?>

另外为大家分享一个函数
在许多收集用户信息的表单里，期望用户输入的是半角字符，但是无论你如何强调，如何提醒，还是会有粗心的用户提交全角数据，其实，在一些新手眼中，全角和半角根本就没有区别，甚至他们会觉得：我提交的明明是正确的信息，为什么会提示错误呢？

实际上，全角和半角有一一对应关系，而大多数用户并非故意输入错误的信息，所以，我们可以通过程序来避免这种情况的发生，最多，可以在转换后给用户一个确认的机会，这样，或许能够给用户一个更好的体验。

下面介绍一个函数，实现字符 半角 和 全角 之间的互转

<?php
header("Content-type: text/html; charset=utf-8");
// 第一个参数：传入要转换的字符串
// 第二个参数：取0，半角转全角；取1，全角到半角
function SBC_DBC($str, $args2) {
    $DBC = Array(
        &#39;０&#39; , &#39;１&#39; , &#39;２&#39; , &#39;３&#39; , &#39;４&#39; ,
        &#39;５&#39; , &#39;６&#39; , &#39;７&#39; , &#39;８&#39; , &#39;９&#39; ,
        &#39;Ａ&#39; , &#39;Ｂ&#39; , &#39;Ｃ&#39; , &#39;Ｄ&#39; , &#39;Ｅ&#39; ,
        &#39;Ｆ&#39; , &#39;Ｇ&#39; , &#39;Ｈ&#39; , &#39;Ｉ&#39; , &#39;Ｊ&#39; ,
        &#39;Ｋ&#39; , &#39;Ｌ&#39; , &#39;Ｍ&#39; , &#39;Ｎ&#39; , &#39;Ｏ&#39; ,
        &#39;Ｐ&#39; , &#39;Ｑ&#39; , &#39;Ｒ&#39; , &#39;Ｓ&#39; , &#39;Ｔ&#39; ,
        &#39;Ｕ&#39; , &#39;Ｖ&#39; , &#39;Ｗ&#39; , &#39;Ｘ&#39; , &#39;Ｙ&#39; ,
        &#39;Ｚ&#39; , &#39;ａ&#39; , &#39;ｂ&#39; , &#39;ｃ&#39; , &#39;ｄ&#39; ,
        &#39;ｅ&#39; , &#39;ｆ&#39; , &#39;ｇ&#39; , &#39;ｈ&#39; , &#39;ｉ&#39; ,
        &#39;ｊ&#39; , &#39;ｋ&#39; , &#39;ｌ&#39; , &#39;ｍ&#39; , &#39;ｎ&#39; ,
        &#39;ｏ&#39; , &#39;ｐ&#39; , &#39;ｑ&#39; , &#39;ｒ&#39; , &#39;ｓ&#39; ,
        &#39;ｔ&#39; , &#39;ｕ&#39; , &#39;ｖ&#39; , &#39;ｗ&#39; , &#39;ｘ&#39; ,
        &#39;ｙ&#39; , &#39;ｚ&#39; , &#39;－&#39; , &#39;　&#39; , &#39;：&#39; ,
        &#39;．&#39; , &#39;，&#39; , &#39;／&#39; , &#39;％&#39; , &#39;＃&#39; ,
        &#39;！&#39; , &#39;＠&#39; , &#39;＆&#39; , &#39;（&#39; , &#39;）&#39; ,
        &#39;＜&#39; , &#39;＞&#39; , &#39;＂&#39; , &#39;＇&#39; , &#39;？&#39; ,
        &#39;［&#39; , &#39;］&#39; , &#39;｛&#39; , &#39;｝&#39; , &#39;＼&#39; ,
        &#39;｜&#39; , &#39;＋&#39; , &#39;＝&#39; , &#39;＿&#39; , &#39;＾&#39; ,
        &#39;￥&#39; , &#39;￣&#39; , &#39;｀&#39;
    );
    $SBC = Array( // 半角
        &#39;0&#39;, &#39;1&#39;, &#39;2&#39;, &#39;3&#39;, &#39;4&#39;,
        &#39;5&#39;, &#39;6&#39;, &#39;7&#39;, &#39;8&#39;, &#39;9&#39;,
        &#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;,
        &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;,
        &#39;K&#39;, &#39;L&#39;, &#39;M&#39;, &#39;N&#39;, &#39;O&#39;,
        &#39;P&#39;, &#39;Q&#39;, &#39;R&#39;, &#39;S&#39;, &#39;T&#39;,
        &#39;U&#39;, &#39;V&#39;, &#39;W&#39;, &#39;X&#39;, &#39;Y&#39;,
        &#39;Z&#39;, &#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;,
        &#39;e&#39;, &#39;f&#39;, &#39;g&#39;, &#39;h&#39;, &#39;i&#39;,
        &#39;j&#39;, &#39;k&#39;, &#39;l&#39;, &#39;m&#39;, &#39;n&#39;,
        &#39;o&#39;, &#39;p&#39;, &#39;q&#39;, &#39;r&#39;, &#39;s&#39;,
        &#39;t&#39;, &#39;u&#39;, &#39;v&#39;, &#39;w&#39;, &#39;x&#39;,
        &#39;y&#39;, &#39;z&#39;, &#39;-&#39;, &#39; &#39;, &#39;:&#39;,
        &#39;.&#39;, &#39;,&#39;, &#39;/&#39;, &#39;%&#39;, &#39;#&#39;,
        &#39;!&#39;, &#39;@&#39;, &#39;&&#39;, &#39;(&#39;, &#39;)&#39;,
        &#39;<&#39;, &#39;>&#39;, &#39;"&#39;, &#39;\&#39;&#39;,&#39;?&#39;,
        &#39;[&#39;, &#39;]&#39;, &#39;{&#39;, &#39;}&#39;, &#39;\\&#39;,
        &#39;|&#39;, &#39;+&#39;, &#39;=&#39;, &#39;_&#39;, &#39;^&#39;,
        &#39;$&#39;, &#39;~&#39;, &#39;`&#39;
    );
    if ($args2 == 0) {
        return str_replace($SBC, $DBC, $str);  // 半角到全角
    } else if ($args2 == 1) {
        return str_replace($DBC, $SBC, $str);  // 全角到半角
    } else {
        return false;
    }
}
$str1 = "http://";
$str2 = "ｈｔｔｐ：／／";
echo "半角 转 全角：<br />";
echo $str1 . &#39; -> &#39; . SBC_DBC($str1, 0);
echo "<br /><br />全角 转 半角：<br />";
echo $str2 . &#39; -> &#39; . SBC_DBC($str2, 1);
?>

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