24 questions that come up in PHP technical interviews, each with the answer and an explanation of why it is right.
Test yourself — 90 question bankAnswer: Functions using yield for memory-efficient iteration
Generators use yield instead of return. Create iterators without storing all values in memory. Memory efficient for large datasets. State preserved between yields.
Answer: Server-side scripting language for web development
PHP (Hypertext Preprocessor) is a popular general-purpose server-side scripting language especially suited for web development. Created by Rasmus Lerdorf.
Answer: Programming paradigm using classes and objects
OOP organizes code into classes (blueprints) and objects (instances). Supports encapsulation, inheritance, polymorphism. Modern PHP is heavily object-oriented.
Answer: <?php and ?>
PHP code blocks start with <?php and end with ?>. Short tags <? ?> exist but are discouraged. Always use <?php for compatibility.
Answer: Declares parameter and return types
Type hints specify parameter/return types: function add(int $a, int $b): int. Enforces types. PHP 7+ has scalar types, return types. Strict mode with declare(strict_types=1).
Answer: class ClassName { properties and methods }
Define class with class keyword: class User { public $name; public function greet() {} }. Convention: PascalCase for class names.
Answer: __construct() method called when object created
__construct() is magic method called automatically when creating object. Initialize properties: function __construct($name) { $this->name = $name; }. PHP 8 has constructor property promotion.
Answer: echo or print
Use echo or print to output text. echo can take multiple parameters, print returns 1. Both work, echo is more common and slightly faster.
Answer: declare(strict_types=1) enforces strict type checking
declare(strict_types=1) at file start enforces strict types. No automatic type coercion. Must be first statement. File-level, not global. Recommended for type safety.
Answer: Functions without names, can capture variables
Anonymous functions: function($x) { return $x * 2; }. Closures capture variables with use: function() use ($var) {}. First-class functions. Used for callbacks.
Answer: $variableName = value
Variables start with $ sign: $name = "John". PHP is loosely typed. Variable names are case-sensitive. Can contain letters, numbers, underscores.
Answer: public, protected, private control access
public: accessible everywhere. protected: class and subclasses. private: only within class. Default is public. Essential for encapsulation.
Answer: Class extends another with extends keyword
Inheritance: class Child extends Parent. Child inherits parent's accessible properties/methods. Override with same method name. Use parent:: to call parent method.
Answer: String, Integer, Float, Boolean, Array, Object, NULL
PHP supports: String, Integer, Float, Boolean, Array, Object, NULL, and Resource. Use gettype() to check type. Type juggling happens automatically.
Answer: static:: refers to called class, not defined class
static:: (not self::) refers to called class at runtime. Enables proper inheritance of static methods. Essential for factory patterns. Resolved at runtime.
Answer: Contract defining methods class must implement
Interface defines method signatures without implementation. Classes implement with implements keyword. Can implement multiple interfaces. All methods are public.
Answer: Use . operator: $a . $b
Concatenate strings with . operator: $full = $first . " " . $last. Use .= for append. String interpolation: "$first $last" in double quotes.
Answer: Functions accepting variable number of arguments with ...
Variadic functions use ...$args to accept variable arguments. function sum(...$numbers). ... also unpacks arrays. PHP 5.6+ feature for flexible functions.
Answer: Cannot be instantiated, may have abstract methods
Abstract class cannot be instantiated. May have abstract methods (no implementation) and concrete methods. Child classes must implement abstract methods.
Answer: Double quotes parse variables, single quotes literal
Double quotes parse variables and escape sequences. Single quotes treat everything literally. "Hello $name" vs 'Hello $name'. Single quotes slightly faster.
Answer: Passes dependencies instead of creating them
Dependency injection passes dependencies to class instead of creating internally. Constructor/setter/interface injection. Enables testing, loose coupling. Core of modern frameworks.
Answer: Manages class dependencies and injection
Service container manages dependencies. Registers services, resolves dependencies automatically. Central to Laravel, Symfony. Enables dependency injection at scale.
Answer: array() or []
Create arrays with array() or [] (short syntax): $arr = [1, 2, 3]. Supports indexed and associative arrays. Dynamic sizing.
Answer: Reusable code for horizontal code reuse
Traits enable code reuse in single inheritance. use TraitName in class. Can use multiple traits. Solves diamond problem. Methods can be aliased or excluded.
The full PHP bank has 90 questions across 3 difficulty levels — timed, shuffled, and scored.
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