Crest Infosystems Interview Questions, Process, and Tips

Q1. What is polymorphism in OOPs ?
Ans. 
Polymorphism in OOPs allows objects of different classes to be treated as objects of a common superclass.
• Polymorphism allows methods to be called on objects of different classes that implement the same interface or superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: Animal superclass with methods like eat() and sleep(). Dog and Cat subclasses can ov...read more
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Q2. What is MySQL injections
Ans. 
MySQL injections are a type of cyber attack where malicious SQL statements are inserted into an entry field for execution.
• MySQL injections occur when an attacker inserts malicious SQL code into a query to manipulate the database.

• Attackers can use MySQL injections to access, modify, or delete data in the database.

• Preventing MySQL injections involves using parameterized queries and input validation.

• Example: SELECT * FROM...read more
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Q3. What is migration in Laravel ?
Ans. 
Migration in Laravel is the process of managing database schema changes using PHP code.
• Migration allows developers to define database tables and their structure using PHP code instead of SQL.

• It helps in version control of database schema changes and makes it easier to collaborate with other developers.

• Migrations can be rolled back to previous states if needed, making database changes reversible.

• Example: 'php artisan ma...read more
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Q4. What's challenges in your last project
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Q5. What's payment integration you did ?
Ans. 
I have integrated payment gateways like PayPal, Stripe, and Square into e-commerce websites.
• Integrated PayPal payment gateway for seamless checkout process

• Implemented Stripe API for secure credit card transactions

• Configured Square payment gateway for in-person and online payments
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Aptitude was based on reasoning and basic tech questions.It was easy.

Q1. Introduce yourself.
Ans. 
I am a passionate Android developer with experience in building mobile applications using Java and Kotlin.
• Experienced in developing Android apps using Java and Kotlin

• Familiar with Android Studio and Android SDK

• Knowledge of RESTful APIs and third-party libraries like Retrofit and Glide
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Q2. How Kotlin is better than Java.
Ans. 
Kotlin is better than Java due to its concise syntax, null safety, interoperability, and improved performance.
• Kotlin has concise syntax which reduces boilerplate code and makes code more readable.

• Kotlin provides null safety features to prevent NullPointerExceptions at runtime.

• Kotlin is fully interoperable with Java, allowing developers to use both languages in the same project.

• Kotlin offers improved performance compare...read more
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Basic javascript questions and verbal reasoning

Q1. Javascript questions, oop, software models
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Q2. Basic react questions, basic dsa
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Basic aptitude questions about profit loss, percentage, a few were tricky but solvable.

Q1. What are different hooks that you've used in react.js
Ans. 
Some common hooks used in React.js are useState, useEffect, useContext, and useRef.
• useState - for managing state in functional components

• useEffect - for handling side effects in functional components

• useContext - for accessing context in functional components

• useRef - for accessing DOM elements or values in functional components
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Q2. What is normalisation in DBMS
Ans. 
Normalization in DBMS is the process of organizing data in a database to reduce redundancy and improve data integrity.
• Normalization involves breaking down a database into smaller, more manageable tables.

• It helps in reducing data redundancy by storing data in a structured way.

• Normalization ensures data integrity by minimizing data anomalies.

• There are different normal forms like 1NF, 2NF, 3NF, BCNF, etc.

• Example: In a dat...read more
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Q3. Basic javascript questions
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