PHP 碎片

1.　$_SERVER['REMOTE_ADDR'] cannot be modified by the user or via HTTP so you CAN trust it. -- 用这个可以有效防止别人跨站提交。
2.  自己写的验证时间格式是否正式的函数：

function checktime($time){
    $time = trim($time);
    if( empty($time) ){
        return false;
    }
    $regStr = "/^20d{2}-d{1,2}-d{1,2} d{1,2}:d{1,2}:d{1,2}$/i";
    if( !preg_match($regStr,$time) ){
        return false;
    }
    $arr = explode(' ',$time);
    $dateStr = $arr[0];
    $timeStr = $arr[1];
    $dateArr = explode('-',$dateStr);
    if( !checkdate($dateArr[1],$dateArr[2],$dateArr[0]) ){
        return false;
    }
    $timeArr = explode(':',$timeStr);
    $hour = intval($timeArr[0]);
    $minute = intval($timeArr[1]);
    $second = intval($timeArr[2]);
    if( $hour>24 || $minute>60 || $second>60 ){
        return false;
    }
    return true;
}

 3.非常好用的调试方法：debug_print_backtrace，可以打印出一个页面的调用过程 , 从哪儿来到哪儿去一目了然。但这个方法是直接输出到页面的，虽然输出页面的东西可以用缓存得到，但也不方便。debug_backtrace，把结果保存到数组，方便很多。使用 debug_print_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS); 简化输出。
 4.

$_POST = array(
    'test' => 1
);

$_REQUEST = $_POST;
$_REQUEST['test'] = 2;

print_r($_REQUEST); 
print_r($_POST);

/*
分别输出
array(
    'test' => 2
);
array(
    'test' => 1
);
*/

$_POST = array(
    'test' => 1
);

$_REQUEST = &$_POST;
$_REQUEST['test'] = 2;

print_r($_REQUEST); 
print_r($_POST);

/*
分别输出
array(
    'test' => 2
);
array(
    'test' => 2
);
*/

 5. 当循环(for)里面有 switch 而我又想用 continue 跳到下一个循环，谁知却是跳出 switch 。

while(){
    switch(){
         case 1:
             xxxx;
             continue; //没有跳出循环，而是跳出了switch
    }
}

 6.curl 的函数

function curl_get($url, $data=array()){
    $ch = curl_init();

    $query = http_build_query($data);
    if(''!=$query) $url .= '?' . $query;

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);

    $result = curl_exec($ch);    
    curl_close($ch);
    return $result;
}

function curl_post($url, $post_data=array()){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
    $result = curl_exec($ch);    
    curl_close($ch);
    return $result;
}