Cognizant Interview Questions and Answers

Software development models are frameworks used to structure, plan, and control the process of developing software.

• Waterfall model

• Agile model

• Spiral model

• Iterative and incremental model

• V-shaped model

• Prototype model

Authentication verifies the identity of a user, while authorization determines what actions a user is allowed to perform.

• Authentication confirms the user's identity through credentials like username and password

• Authorization controls access to resources based on the authenticated user's permissions

• Example: Logging into a system (authentication) vs. accessing specific files or features within the system (authorization)

Async functions in JavaScript allow for asynchronous programming using the async/await syntax.

• Async functions are defined using the 'async' keyword before the function declaration.

• They allow for the use of the 'await' keyword within the function to pause execution until a promise is settled.

• Async functions always return a promise.

• Example: async function fetchData() { await fetch('https://api.example.com/data'); }

Node modules are reusable code packages that can be easily imported and used in Node.js applications.

• Node modules are JavaScript libraries that can be easily installed using npm (Node Package Manager).

• They help in organizing code, improving code reusability, and managing dependencies.

• Examples of popular node modules include Express.js for web applications, Lodash for utility functions, and Mongoose for MongoDB interactions.

Runtime polymorphism is the ability of a function to behave differently based on the object it is called with.

• Runtime polymorphism is achieved through method overriding in object-oriented programming.

• It allows a subclass to provide a specific implementation of a method that is already provided by its superclass.

• The actual method that gets called is determined at runtime based on the type of object.

• Example: Animal class has a method 'makeSound', Dog and Cat classes override th...read more

Promises are objects representing the eventual completion or failure of an asynchronous operation.

• Promises are used to handle asynchronous operations in JavaScript.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained together using .then() to handle success and failure.

• Example: new Promise((resolve, reject) => { ... }).then(result => { ... }).catch(error => { ... });

C is a procedural programming language while C++ is a multi-paradigm programming language with object-oriented features.

• C is a procedural programming language, while C++ supports both procedural and object-oriented programming.

• C does not support classes and objects, while C++ does.

• C does not have features like inheritance, polymorphism, and encapsulation, which are supported in C++.

• C++ has additional features like templates, exceptions handling, and namespaces which are not p...read more

Polymorphism is the ability of a function or method to behave differently based on the object it is acting upon.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• It enables a single interface to represent multiple data types.

• Examples include method overloading and method overriding in object-oriented programming.