php新人请求知道，关于post传递的问题

<?phpecho "Welcome to my world!";echo "Welcome," . $_POST['name'];echo "You are " . $_POST['age'] . " old .";

<?phpecho "Welcome to my world!";echo "Welcome," . $_POST['name'];echo "You are " . $_POST['age'] . " years old .";

<?=$_POST['a']?>

<?php/**  * 发送post请求  * @param string $url 请求地址  * @param array $post_data post键值对数据  * @return string  * @edit by www.jbxue.com */  function send_post($url, $post_data) {      $postdata = http_build_query($post_data);    $options = array(      'http' => array(        'method' => 'POST',        'header' => 'Content-type:application/x-www-form-urlencoded',        'content' => $postdata,        'timeout' => 15 * 60 // 超时时间（单位:s）      )    );    $context = stream_context_create($options);    $result = file_get_contents($url, false, $context);      return $result;  }    //使用方法  $post_data = array(    'username' => 'stclair2201',    'password' => 'handan'  );  send_post('http://www.qianyunlai.com', $post_data);          <?php  /**  * Socket版本  * 使用方法：  * $post_string = "app=socket&version=beta";  * request_by_socket('chajia8.com', '/restServer.php', $post_string);  */  function request_by_socket($remote_server,$remote_path,$post_string,$port = 80,$timeout = 30) {    $socket = fsockopen($remote_server, $port, $errno, $errstr, $timeout);    if (!$socket) die("$errstr($errno)");    fwrite($socket, "POST $remote_path HTTP/1.0");    fwrite($socket, "User-Agent: Socket Example");    fwrite($socket, "HOST: $remote_server");    fwrite($socket, "Content-type: application/x-www-form-urlencoded");    fwrite($socket, "Content-length: " . （strlen($post_string) + 8） . "");    fwrite($socket, "Accept:*/*");    fwrite($socket, "");    fwrite($socket, "mypost=$post_string");    fwrite($socket, "");    $header = "";    while ($str = trim(fgets($socket, 4096))) {      $header .= $str;    }      $data = "";    while (!feof($socket)) {      $data .= fgets($socket, 4096);    }      return $data;  }  ?>    <?php  /**   * Curl版本   * 使用方法：   * $post_string = "app=request&version=beta";   * request_by_curl('http://www.qianyunlai.com/restServer.php', $post_string);   */  function request_by_curl($remote_server, $post_string) {    $ch = curl_init();    curl_setopt($ch, CURLOPT_URL, $remote_server);    curl_setopt($ch, CURLOPT_POSTFIELDS, 'mypost=' . $post_string);    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);    curl_setopt($ch, CURLOPT_USERAGENT, "qianyunlai.com's CURL Example beta");    $data = curl_exec($ch);    curl_close($ch);      return $data;  }  ?>