达内php面试题,2015经典php笔试题与答案

以下是一些经典的PHP笔试题及其答案：

1. PHP中如何打印输出变量的值？

答案：可以使用echo或print语句来打印输出变量的值，例如：

$var = "Hello, world!";
echo $var;
print $var;

2. PHP中如何定义一个常量？

答案：可以使用define()函数来定义一个常量，例如：

define("PI", 3.14159);
echo PI;

3. PHP中如何连接MySQL数据库？

答案：可以使用mysqli_connect()函数来连接MySQL数据库，例如：

$host = "localhost";
$user = "username";
$password = "password";
$database = "my_db";

$conn = mysqli_connect($host, $user, $password, $database);

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";

4. PHP中如何执行SQL查询语句？

答案：可以使用mysqli_query()函数来执行SQL查询语句，例如：

$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"] . " - Email: " . $row["email"] . "<br>";
    }
} else {
    echo "0 results";
}

5. PHP中如何上传文件？

答案：可以使用$_FILES数组来上传文件，例如：

<form action="upload.php" method="post" enctype="multipart/form-data">
    Select file to upload:
    <input type="file" name="fileToUpload" id="fileToUpload">
    <input type="submit" value="Upload File" name="submit">
</form>

<?php
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));

if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        echo "File is an image - " . $check["mime"] . ".";
        $uploadOk = 1;
    } else {
        echo "File is not an image.";
        $uploadOk = 0;
    }
}

if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>

这些是一些经典的PHP笔试题及其答案，希望对你有所帮助。