收集整理常用php函数１

１、计算文件单位大小函数

function cheksize($size) {
        $size = floatval($size);
        $rate_k = 1024 ;
        $rate_m = 1024 * 1024;
        $rate_g = 1024 * 1024 * 1024;
        $new_size = $size / $rate_g;
        if ($new_size < 1) {
                $new_size = $size / $rate_m;
                if ($new_size < 1) {
                        $new_size = round($size / $rate_k,2) . 'K';
                        if ($new_size == '0K') {
                                $new_size = "N/A";
                        }
                } else
                $new_size = round($new_size,2) . 'M';
        } else
                $new_size = round($new_size,2) . 'G';
        return $new_size;
}

２、删除数组中的空元素，并且不会打乱数组内部序号

function array_remove_empty(&$arr, $trim = true){
        foreach ($arr as $key => $value){
                if (is_array($value)){
                        array_remove_empty($arr[$key]);
                } else{
                        $value = trim($value);
                        if ($value == ''){
                                unset($arr[$key]);
                        } elseif ($trim){
                                $arr[$key] = $value;
                        }
                }
        }
}

3、检测客户端系统操作类型的函数

function sysinfo($agent){
        $sys="";
        if (stristr('win',$agent) && stristr('nt 5\.1',$agent)) {
                $sys="Windows XP";
        }elseif (stristr('win',$agent) && strstr('98',$agent))  {
                $sys="Windows 98";
        }       elseif (stristr('win',$agent) && stristr('nt 5\.0',$agent))     {
                $sys="Windows 2000";
        }       elseif (stristr('win 9x',$agent) && strpos($agent, '4.90')) {
                $sys="Windows ME";
        }       elseif (stristr('win',$agent) && strpos($agent, '95'))  {
                $sys="Windows 95"; 
    }   elseif (stristr('win',$agent) && stristr('nt',$agent))  {
                $sys="Windows NT";
    }   elseif (stristr('win',$agent) && strstr('32',$agent))   {
                $sys="Windows 32";
        }       elseif (stristr('linux',$agent)) {
                $sys="Linux";
        }       elseif (stristr('unix',$agent)) {
                $sys="Unix";
        }       elseif (stristr('ibm',$agent) && stristr('os',$agent))  {
                $sys="IBM OS/2";
        }       elseif (stristr('NetBSD',$agent)) {
                $sys="NetBSD";
        }       elseif (stristr('BSD',$agent)) {
                $sys="BSD";
        }       elseif (stristr('FreeBSD',$agent))      {
                $sys="FreeBSD";
        }       else
                $sys = "Unknown";
        return $sys;
}