PHP截取中英文

<code><span>/**
     *<span> @param</span> $string
     *<span> @param</span> $from   从0开始……
     *<span> @param</span> null $length
     *<span> @return</span> string
     * c_substr("给我一点", $from=0, 9)>>给我一
     * c_substr("给我一点", $from=1, 9)>>我一
     * c_substr("给我一点", $from=2, 9)>>我一
     * c_substr("给我一点", $from=3, 9)>>我一点
     */</span><span>private</span><span><span>function</span><span>c_substr</span><span>(<span>$string</span>, <span>$from</span>=<span>0</span>, <span>$length</span> = null)</span>{</span><span>//必填字段校验</span><span>if</span>(!<span>isset</span>(<span>$string</span>)||!<span>isset</span>(<span>$from</span>)||<span>$from</span><<span>0</span>){
            <span>return</span><span>''</span>;
        }
        <span>//获得字符串长度</span><span>$strLen</span> = strlen(<span>$string</span>);
        <span>//如果没有设置长度则把长度设置为字符串</span><span>if</span>(<span>$length</span>  == <span>null</span>){
            <span>$length</span> = <span>$strLen</span>;
        }
        <span>//判断字符串长度是否小于等于$length，是则直接返回字符串</span><span>if</span>(<span>$from</span> == <span>0</span>&&<span>$length</span> >= <span>$strLen</span>){
            <span>return</span><span>$string</span>;
        }
        <span>$subLen</span> = <span>$length</span> + <span>$from</span>;
        <span>$rtnStr</span> = <span>""</span>;
        <span>//开始截取字符串</span><span>//为了能够截取完整，需要从头开始遍历</span><span>for</span>(<span>$i</span>=<span>0</span>;<span>$i</span><<span>$subLen</span>&&<span>$i</span><<span>$strLen</span>;<span>$i</span>++){
            <span>//判断是否为中文 如果是则在不超长的情况下往后再截2个字节</span><span>if</span>(ord(<span>$string</span>[<span>$i</span>])><span>0xa0</span>){
                <span>if</span>(<span>$i</span>+<span>2</span><<span>$subLen</span>&&<span>$i</span>+<span>2</span><<span>$strLen</span>){
                    <span>$rtnStr</span> .= <span>$string</span>[<span>$i</span>].<span>$string</span>[<span>$i</span>+<span>1</span>].<span>$string</span>[<span>$i</span>+<span>2</span>];
                    <span>/**
                     * 如 “给我一点”
                     * 从位置0截取9个字节，则只获取“给我一”
                     * 从位置1截取9个字节，则只获取“我一”
                     * 从位置2截取9个字节，则只获取“我一”
                     * 从位置3截取9个字节，则只获取“我一点”
                     * 下面的if是为了跳过开头不完整的字符
                    */</span><span>if</span>(<span>$i</span><<span>$from</span>){
                        <span>$rtnStr</span> = <span>""</span>;
                    }
                    <span>$i</span> += <span>2</span>;
                }
                <span>else</span>{
                    <span>return</span><span>$rtnStr</span>;
                }
            }
            <span>//英文</span><span>else</span>{
                <span>$rtnStr</span> .= <span>$string</span>[<span>$i</span>];
            }
        }
        <span>return</span><span>$rtnStr</span>;
    }</code>