php取得字符串首字母的方法

本文实例讲述了php取得字符串首字母的方法。分享给大家供大家参考。具体实现方法如下：

    <?php
    $limit = array( //gb2312 拼音排序
      array(45217,45252), //A
      array(45253,45760), //B
      array(45761,46317), //C
      array(46318,46825), //D
      array(46826,47009), //E
      array(47010,47296), //F
      array(47297,47613), //G
      array(47614,48118), //H
      array(0,0),     //I
      array(48119,49061), //J
      array(49062,49323), //K
      array(49324,49895), //L
      array(49896,50370), //M
      array(50371,50613), //N
      array(50614,50621), //O
      array(50622,50905), //P
      array(50906,51386), //Q
      array(51387,51445), //R
      array(51446,52217), //S
      array(52218,52697), //T
      array(0,0),     //U
      array(0,0),     //V
      array(52698,52979), //W
      array(52980,53688), //X
      array(53689,54480), //Y
      array(54481,55289), //Z
    );
    $str="A:这是一个测试程序1";
    $str= iconv("UTF-8","gb2312", $str);
    echo $str."</br>";
    $i=0;
    while($i<strlen($str) ) {
      $tmp=bin2hex(substr($str,$i,1));
      if($tmp>='B0'){ //汉字的开始
        $t=getLetter(hexdec(bin2hex(substr($str,$i,2))));
        printf("%c",$t==-1 ? '*' : $t );
        $i+=2;
      }
      else{
        printf("%s",substr($str,$i,1));
        $i++;
      }
    }
    function getLetter($num){
      global $limit;
      $char_index=65;
      foreach($limit as $k=>$v){
        if($num>=$v[0] && $num<=$v[1]){
          $char_index+=$k;
          return $char_index;
        }
      }
      return -1;
    }
    ?>

希望本文所述对大家的php程序设计有所帮助。