Php Lead Interview Questions and Answers

Interface defines only method signatures while abstract class can have both method signatures and implementations.

• Interface cannot have method implementations, only method signatures.

• Abstract class can have both method signatures and implementations.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Interfaces are used to define a contract for classes to implement, while abstract classes are used to provide a common base for subclasses.

InnoDB is a transaction-safe storage engine for MySQL, while MyISAM is not transaction-safe.

• InnoDB supports transactions with ACID properties, while MyISAM does not.

• InnoDB supports foreign keys, while MyISAM does not.

• InnoDB is more reliable and crash-safe compared to MyISAM.

• InnoDB is the default storage engine for MySQL 5.5 and higher versions.

• MyISAM is faster for read-heavy operations, while InnoDB is better for write-heavy operations.

array_map in PHP is used to apply a callback function to each element of an array.

• array_map() returns an array containing all the elements of the input array after applying the callback function to each one.

• It is useful for applying a function to all elements of an array without using a loop.

• Example: array_map('strtoupper', ['apple', 'banana', 'cherry']) will return ['APPLE', 'BANANA', 'CHERRY'].

A callback function in PHP is a function that is passed as an argument to another function and is executed at a later time.

• Callback functions are commonly used in PHP for event handling, asynchronous processing, and custom sorting.

• Example: array_map() function in PHP takes a callback function as an argument to apply a user-defined function to each element of an array.

• Another example: usort() function in PHP uses a callback function to define custom sorting logic for an array.

A static method is a method that belongs to the class itself, rather than to instances of the class.

• Static methods can be called directly on the class without needing to create an instance of the class.

• Static methods are commonly used for utility functions that do not require access to instance-specific data.

• Static methods are declared using the 'static' keyword in PHP.

PHPUnit workflow involves writing test cases, running tests, and analyzing results.

• Write test cases using PHPUnit framework

• Run tests using PHPUnit command line interface or IDE integration

• Analyze test results to identify failures and errors

• Make necessary code changes to fix failing tests

• Repeat the process until all tests pass successfully