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HomeBackend DevelopmentPHP Tutorialphp采集速度探究总结(原创)_php技巧

 
注意:下面的所有函数都没有用正则。

以上为取出第一个匹配的三个函数,实现相同的目的

function str_cut($str ,$start, $end) {//取出第一个匹配,效率最高,先分割再替换
$content = strstr( $str, $start );
$content = substr( $content, strlen( $start ), strpos( $content, $end ) - strlen( $start ) );
return $content;
}
function str_cut1($str ,$start, $end) {//取出第一个匹配,效率中,直接查找替换
$x = strpos($str, $start);
return substr($str, $x+strlen($start), strpos($str, $end)-$x+strlen($end));
}

function str_cut3($content,$start,$end){//取出第一个匹配,字符串越大,速度越慢!
$my = explode($start,$content);
$my = explode($end,$my[1]);
return $my[0];
}

以下为取出所有匹配的3个函数(全部原创),实现相同的采集目的


function strcut($str ,$start, $end) //先搜个数,速度中等
{
    if( strpos( $str , $start ) )
    {
            $sum = substr_count($str,$start);

            $carr = array();
            for($i=0;$i                $str = strstr( $str, $start );
                $str = substr( $str, strlen($start));
                   $carr[] = substr( $str, 0, strpos( $str, $end ) );
            }

          

    }
    return $carr;
}

function str_cut_all($str ,$start, $end,$carr=array()) //递归,运行效率最慢!
{
    if( strpos( $str , $start ) )
    {
            $str = strstr( $str, $start );
            $str = substr( $str, strlen($start));
               $carr[] = substr( $str, 0, strpos( $str, $end ) );
               if( strpos( $str , $start ) )
            {
                   return str_cut_all($str ,$start, $end ,$carr );
               }

    }
    return $carr;
}

function my_Ca($content,$start,$end){//取出所有匹配,效率最快,因为只读一次,字符串越大越明显
    $m = explode($start,$content);
    $a = array();
    for( $i = 1;$i     {
        $my = explode($end,$m[$i]);
        $a[] = $my[0];
        unset($my);
    }
    return $a;
}

注意my-Ca比较
如果这样写:

function my_Ca($content,$start,$end){//取出所有匹配
$m = explode($start,$content);
$a = array();
$sum = count($m);
for( $i = 1;$i {
$my = explode($end,$m[$i]);
$a[] = $my[0];
unset($my);
}
return $a;
}

速度又快了一些!


由上可以看出,并不是数组处理函数(explode)比字符串处理函数(substr等)慢,也不是那个比这个快,因为在匹配多个数据的时候匹配的越多数组函数的优势越大,处理字符串就象切蛋糕一样越切越小。匹配单个字符串运用切的思路去做也是一样的效果(str_cut)。关键还是在---算法!算法写的好,什么函数都是一样哦!

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