Stage 5 - Collections, LINQ, and Strings
Q32. What is a collection?
Quick interview answer:
A collection stores multiple items in one object.
Common examples are List<T> for ordered data, Dictionary<TKey, TValue> for key-based lookup, and HashSet<T> for unique values.
Study in detail: Collections - This article expands the topic with complete explanation, examples, and practice code.
Q33. When should we use Dictionary?
Quick interview answer:
Use Dictionary when you want to find a value quickly using a key.
For example, we can find a student by admission number instead of searching the whole list.
Study in detail: Collections - This article expands the topic with complete explanation, examples, and practice code.
Q34. What is LINQ?
Quick interview answer: LINQ is a way to query data using C# syntax. It helps us filter, sort, group, and select data from collections, databases, and other sources in a readable way.
var passedStudents = students
.Where(s => s.Marks >= 35)
.ToList();
Study in detail: LINQ - This article expands the topic with complete explanation, examples, and practice code.
Q35. What is deferred execution in LINQ?
Quick interview answer:
Deferred execution means a LINQ query does not run immediately when it is created.
It runs only when we read the result, such as with foreach, ToList(), Count(), or FirstOrDefault().
Study in detail: LINQ and Iterators - This article expands the topic with complete explanation, examples, and practice code.
Q36. Why are strings immutable?
Quick interview answer:
Strings are immutable, which means once a string is created it cannot be changed.
When we modify a string, C# creates a new string. For many repeated changes, StringBuilder is more efficient.
Study in detail: Strings - This article expands the topic with complete explanation, examples, and practice code.