Common validation patterns in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is input validation in PHP?

Input validation is the process of checking user input to ensure it meets expected formats and rules before processing it. This helps prevent errors and security issues.

beginner

How do you validate an email address in PHP?

Use the filter_var() function with FILTER_VALIDATE_EMAIL to check if a string is a valid email format.

beginner

What PHP function helps validate if a string contains only letters and numbers?

ctype_alnum() checks if all characters in the string are letters or digits.

intermediate

Why is it important to validate data on the server side in PHP?

Server-side validation ensures data is safe and correct even if client-side validation is bypassed. It protects against malicious input and errors.

beginner

What is a common pattern to validate a required field in PHP?

Check if the field is set and not empty using isset() and !empty() functions before processing.

Which PHP function validates an email format?

A is_numeric()

B ctype_alpha()

C filter_var() with FILTER_VALIDATE_EMAIL

D preg_match() with /[0-9]/

filter_var() with FILTER_VALIDATE_EMAIL checks if the input is a valid email address.

How do you check if a string contains only letters and numbers in PHP?

A filter_var()

B is_string()

C strlen()

D ctype_alnum()

ctype_alnum() returns true if all characters are letters or digits.

What does the PHP function isset() check?

A If a variable is set and not NULL

B If a string is empty

C If a number is positive

D If an array contains values

isset() returns true if the variable exists and is not NULL.

Why should validation be done on the server side?

A To prevent bypassing client-side checks and protect data

B To make the page load faster

C To improve CSS styling

D To reduce server load

Server-side validation ensures security and data integrity even if client-side validation is skipped.

Which PHP function can be used to check if a string matches a pattern?

A strlen()

B preg_match()

C is_array()

D trim()

preg_match() checks if a string matches a regular expression pattern.

Explain how to validate an email address in PHP and why it is important.

Think about built-in PHP functions for filtering.

Describe the difference between client-side and server-side validation and why server-side validation is necessary.

Consider what happens if a user disables JavaScript.