C2fo Software Engineer2 Interview Questions and Answers

Q1. Asked to write a program to check whether string is valid or not. String consists of only three kind of special characters "(), [], {}". We need to return true if all special characters are in correct for...read more
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Q2. What is useRef hook used for?
Ans. 
useRef hook is used to persist a mutable value across renders without causing a re-render.
• Used to store mutable values that do not trigger re-renders.

• Commonly used for accessing DOM elements or storing previous values.

• Does not cause a re-render when the value changes.
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Q3. What are the best practices to avoid rerenders and to improve performance
Ans. 
Use memoization, virtual DOM, and shouldComponentUpdate to avoid unnecessary rerenders and improve performance.
• Implement memoization to store the result of expensive function calls and avoid recalculating them.

• Use virtual DOM to efficiently update only the parts of the UI that have changed.

• Override shouldComponentUpdate to prevent unnecessary rerenders by comparing current and next props/state.
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Q4. What are callbacks, Promises, async await
Ans. 
Callbacks, Promises, async await are asynchronous programming concepts in JavaScript.
• Callbacks are functions passed as arguments to another function to be executed later.

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

• async await is a syntax for writing asynchronous code that looks synchronous, making it easier to read and maintain.

• Example: Using a callback to handle th...read more
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Three coding online assessments - screening round.

Two to three coding questions based on dynamic programming.

Q1. Resume based and computer network
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Q1. Simple hr question
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Q1. What is string eplain that code
Ans. 
A string is a sequence of characters used to represent text.
• Strings are typically enclosed in quotation marks

• Strings can contain letters, numbers, symbols, and spaces

• Strings can be manipulated using various string functions
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Q2. What is array how type of array
Ans. 
An array is a data structure that stores a collection of elements of the same type in a contiguous memory location.
• Arrays can be of different types such as integer arrays, float arrays, or string arrays.

• Example: string[] names = {"Alice", "Bob", "Charlie"};

• Arrays in most programming languages are zero-indexed, meaning the first element is at index 0.

• Arrays allow for efficient access and manipulation of elements based o
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Very few question asking like time and work

Q1. Difference between exe and dll
Ans. 
Exe is an executable file that can be run independently, while DLL is a dynamic link library that is loaded by programs when needed.
• Exe stands for executable file, while DLL stands for dynamic link library.

• Exe files can be run independently, while DLL files are loaded by programs when needed.

• Exe files have their own memory space, while DLL files share memory space with the calling process.

• Exe files are typically larger...read more
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Q2. What are http verbs
Ans. 
HTTP verbs are used to indicate the action to be performed on a resource in a RESTful API.
• GET - retrieve data from a server

• POST - send data to a server to create/update a resource

• PUT - update a resource on the server

• DELETE - remove a resource from the server

• PATCH - partially update a resource on the server
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Q3. What is method overloading and overriding Output based question
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Q4. Linq query to filter data and group by
Ans. 
Use Linq query to filter data and group by in C#
• Use 'Where' method to filter data based on a condition

• Use 'GroupBy' method to group the filtered data based on a key

• Example: var result = data.Where(x => x.Property == value).GroupBy(x => x.GroupKey)
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Q5. Attribute in mvc
Ans. 
An attribute in MVC is a piece of metadata that provides additional information about a model, view, or controller.
• Attributes are used to add behavior or data to a class or method in MVC

• They can be used for validation, authorization, caching, etc.

• Examples include [Required], [Authorize], [OutputCache]
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90 mins, easy, Data structures and algorithm basics

Q1. Given an array, remove all duplicates in place
Ans. 
Remove duplicates from array of strings in place
• Use a HashSet to keep track of unique elements

• Iterate through the array and remove duplicates by checking if element is already in the HashSet

• Update the array in place by shifting elements to fill in the removed duplicates
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Q1. Caching and its uses
Ans. 
Caching is the process of storing data in a temporary location to reduce access time and improve performance.
• Caching helps reduce the load on servers by serving frequently accessed data quickly

• It can improve performance by reducing the time needed to retrieve data from the original source

• Examples include browser caching, CDN caching, and database caching
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Q1. Personality grading
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Q1. 2 code and 2 MySQL query
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Basic aptitude with tracing program

3 problem with easy to hard