PHP form validation: commonly used data type validation functions

PHP form validation: commonly used data type validation functions

When developing web applications, forms are one of the essential components. User-entered data needs to be verified to ensure data integrity and accuracy. PHP provides a series of functions to validate various data types. This article will introduce some commonly used data type validation functions and how to use them to validate form data.

1. Validate string

String validation is one of the most commonly used validations. In forms, we often need to verify user name, password, email and other string type data entered by the user.

1.1. Verify non-empty string

Use the empty() function to verify whether a string is empty. empty() The function will return true if the string is empty, and false if the string is not empty.

// 验证用户名
if (empty($_POST['username'])) {
    $errors[] = '请输入用户名';
}

// 验证密码
if (empty($_POST['password'])) {
    $errors[] = '请输入密码';
}

1.2. Verify the length of the string

Use the strlen() function to verify whether the length of the string meets the requirements. For example, verify that the password is between 6 and 12 characters long.

$password = $_POST['password'];

if (strlen($password) < 6 || strlen($password) > 12) {
    $errors[] = '密码长度必须在6到12个字符之间';
}

1.3. Verify specific characters

Use the preg_match() function to verify whether a string matches a specific regular expression. For example, verify that the email address is in the correct format.

$email = $_POST['email'];

if (!preg_match("/^w+([.-]?w+)*@w+([.-]?w+)*(.w{2,3})+$/", $email)) {
    $errors[] = '邮箱格式不正确';
}

2. Validate values

Numerical validation is mainly used to verify numeric data in forms, such as age, phone number, etc.

2.1. Verify whether it is an integer

Use the is_int() function to verify whether a value is an integer.

$age = $_POST['age'];

if (!is_int($age)) {
    $errors[] = '年龄必须是整数';
}

2.2. Verify the numerical range

Use the filter_var() function to verify whether a value is within the specified range. For example, verify if the age is between 18 and 60.

$age = $_POST['age'];

if (!filter_var($age, FILTER_VALIDATE_INT, array('options' => array('min_range' => 18, 'max_range' => 60)))) {
    $errors[] = '年龄必须在18到60之间';
}

3. Validation date

Date validation is used to validate date type data in the form, such as birthday, appointment date, etc.

3.1. Verify date format

Use the strtotime() function to convert a string into a timestamp and verify whether the date format is correct.

$birthday = $_POST['birthday'];

if ($birthday && !strtotime($birthday)) {
    $errors[] = '生日格式不正确';
}

3.2. Verify date range

Use the strtotime() function to convert a string into a timestamp and verify whether the date is within the specified range. For example, verify if the appointment date is within the next 7 days.

$appointment_date = $_POST['appointment_date'];

if ($appointment_date && (strtotime($appointment_date) < time() || strtotime($appointment_date) > strtotime('+7 days'))) {
    $errors[] = '预约日期必须在未来7天内';
}

The above are some commonly used data type verification functions and sample codes. In actual development, these functions can be combined to verify form data according to specific requirements and validation rules. Through effective data verification, users can avoid entering incorrect or malicious data and improve the security and stability of the system.

Summary

PHP provides a series of verification functions that can easily verify different types of data. In forms, proper data validation is critical to protecting the integrity and accuracy of your data. By using these validation functions properly, we can easily validate form data and detect and handle user input errors in a timely manner.

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