麻煩用PHP（調用非對象的成員函數）

Question

我得到這個PHP錯誤，我似乎無法修復它。

Fatal error: Call to a member function prepare() on a non-object in C:\xampp\htdocs\mlrst\database.php on line 26 

這裏是調用函​​數prepare的行。

$this->statement->prepare($strQuery); 

這裏是它的聲明。

protected $statement; 

有什麼想法嗎？

編輯：這是我的全部代碼（不介意測試假人）

<?php 

$d = new database(); // test 

class database { 

protected $db_connect; 
protected $statement; 

function database() { 
    $db_connect = new MySQLi("localhost", "root" ,"", "test") or die("Could not connect to the server."); 
    $statement = $db_connect->stmt_init(); 
    $this->preparedQuery("INSERT INTO feedback (name, feedback) VALUES ('?', '?')"); 
    $this->close(); 
    echo "Done!"; 
} 

protected function cleanString($strLine) { 
    $strCleansedLine = preg_replace("/[^a-zA-Z0-9\s]/", "", $strLine); 
    return $strCleansedLine; 
} 

public function preparedQuery($strQuery, $parameters = NULL) { 
    try { 
     $this->statement->prepare($strQuery); 
     $statement->bind_param("ss", $name, $feedback); 

     for ($i = 0; $i < count($parameters); $i++) { 

     } 
     $name = $this->cleanString("this is my name"); 
     $feedback = $this->cleanString("this is some feedback"); 
     $query = $statement->execute(); 
    } catch(Exception $e) { 
     echo $e->getMessage(); 
    } 
} 

protected function close() { 
    try { 
     if ($this->statement != NULL) 
      $this->statement->close(); 
     if ($this->db_connect != NULL) 
      $this->db_connect->close(); 
    } catch (Exception $e) { 
     $e->getMessage(); 
    } 
} 
} 
?> 

Answer 1

您指定的局部變量$statement。您需要使用$this->statement來設置實例的屬性。

換句話說，改變這種：

$statement = $db_connect->stmt_init(); 

要這樣：

$this->statement = $db_connect->stmt_init(); 

這：

$statement->bind_param("ss", $name, $feedback); 

要這樣：

$this->statement->bind_param("ss", $name, $feedback); 

...這：

$query = $statement->execute(); 

要這樣：

$query = $this->statement->execute();