深入了解PHP：從入門到精通

深入了解PHP：從入門到精通

引言：
PHP是一種廣泛應用於web開發的伺服器端腳本語言，它簡單易學，適用於初學者，也提供了豐富的功能和擴充性，能夠滿足複雜的開發需求。本文將從入門到精通，透過具體的程式碼範例，帶您逐步了解PHP的各個面向。

一、基礎知識

1. 變數宣告與輸出

   $name = "John";
   $age = 25;
   echo "My name is " . $name . " and I am " . $age . " years old.";

2. 條件語句

   $score = 90;
   if ($score >= 60) {
    echo "You passed the exam!";
   } else {
    echo "You failed the exam.";
   }

3. 循環語句

   for ($i = 0; $i < 5; $i++) {
    echo $i;
   }

4. 函數的定義和呼叫

   function sayHello($name) {
    echo "Hello, " . $name . "!";
   }
   sayHello("Tom");

二、陣列和字串

1. 陣列的宣告與遍歷

   $fruits = ["apple", "banana", "orange"];
   foreach ($fruits as $fruit) {
    echo $fruit;
   }

2. 字串運算

   $str = "Hello, PHP!";
   echo strlen($str);  // 输出：12
   echo strtoupper($str);  // 输出：HELLO, PHP!
   echo substr($str, 7);  // 输出：PHP!

三、資料庫操作

1. ##連接資料庫

   $servername = "localhost";
   $username = "root";
   $password = "123456";
   $dbname = "myDB";
   $conn = mysqli_connect($servername, $username, $password, $dbname);
   if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
   }

2. 查詢資料

   $sql = "SELECT * FROM users";
   $result = mysqli_query($conn, $sql);
   if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "Name: " . $row['name'] . ", Age: " . $row['age'];
    }
   } else {
    echo "No results found.";
   }

3. 插入資料

   $sql = "INSERT INTO users (name, age) VALUES ('John', 25)";
   if (mysqli_query($conn, $sql)) {
    echo "Data inserted successfully.";
   } else {
    echo "Error: " . mysqli_error($conn);
   }

四、物件導向程式設計

1. 類別的定義和實例化

   class Car {
    public $color;
    public function drive() {
        echo "Driving...";
    }
   }
   $car = new Car();
   $car->color = "red";
   $car->drive();

2. 繼承和多態

   class SportsCar extends Car {
    public function drive() {
        echo "Driving at high speed!";
    }
   }
   $sportsCar = new SportsCar();
   $sportsCar->color = "blue";
   $sportsCar->drive();

五、常見應用程式

1. 檔案上傳

   <form action="upload.php" method="POST" enctype="multipart/form-data">
    <input type="file" name="file">
    <input type="submit" value="Upload">
   </form>

   $targetDir = "uploads/";
   $targetFile = $targetDir . basename($_FILES["file"]["name"]);
   if (move_uploaded_file($_FILES["file"]["tmp_name"], $targetFile)) {
    echo "File uploaded successfully.";
   } else {
    echo "Error uploading file.";
   }

2. 用戶註冊與登入

   $hashedPassword = password_hash($password, PASSWORD_DEFAULT);
   $sql = "INSERT INTO users (username, password) VALUES ('$username', '$hashedPassword')";
   if (mysqli_query($conn, $sql)) {
    echo "Registration successful. You can now login.";
   } else {
    echo "Error: " . mysqli_error($conn);
   }

   $sql = "SELECT * FROM users WHERE username = '$username'";
   $result = mysqli_query($conn, $sql);
   if (mysqli_num_rows($result) > 0) {
    $row = mysqli_fetch_assoc($result);
    if (password_verify($password, $row['password'])) {
        echo "Login successful.";
    } else {
        echo "Password incorrect.";
    }
   } else {
    echo "Username not found.";
   }

#結論：

透過本文的介紹和實例程式碼，希望讀者能夠從PHP的基礎知識開始，逐步深入了解PHP的各個方面，從而掌握PHP的高階應用技巧，提升自己的開發能力。同時，也歡迎讀者在實務上探索更多有趣且創新的PHP應用。

以上是深入了解PHP：從入門到精通的詳細內容。更多資訊請關注PHP中文網其他相關文章！