如何在PHP中实现数据排序

// 源数据
$data = array(5, 3, 8, 2, 1);

// 使用内置函数进行排序
sort($data);

// 输出排序结果
foreach ($data as $value) {
    echo $value . " ";
}

如何在PHP中实现字符串替换

// 源字符串
$str = "Hello, World!";

// 使用内置函数替换字符串
$newStr = str_replace("Hello", "Hi", $str);

// 输出替换后的结果
echo $newStr;

如何在PHP中实现文件读写

// 打开文件并写入内容
$filename = "example.txt";
$file = fopen($filename, "w");
fwrite($file, "Hello, World!");
fclose($file);

// 读取文件内容并输出
$file = fopen($filename, "r");
$content = fread($file, filesize($filename));
fclose($file);
echo $content;

如何在PHP中实现数组操作

// 创建一个空数组
$array = array();

// 添加元素到数组
$array[] = "apple";
$array[] = "banana";
$array[] = "orange";

// 遍历数组并输出
foreach ($array as $value) {
    echo $value . " ";
}

// 获取数组长度
$length = count($array);
echo "Array length: " . $length;

如何在PHP中实现数据库连接与操作

// 连接到数据库
$servername = "localhost";
$username = "root";
$password = "123456";
$dbname = "mydb";
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 执行SQL查询
$sql = "SELECT * FROM users";
$result = $conn->query($sql);

// 输出查询结果
if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "ID: " . $row["id"] . ", Name: " . $row["name"] . "
";
    }
} else {
    echo "0 结果";
}

// 关闭数据库连接
$conn->close();