
Practice 50 C# LINQ Programming Questions
Q1. Write a C# program to find all even numbers from a list of integers using LINQ.
Input: numbers = { 1, 2, 3, 4, 5, 6 }
Output: 2, 4, 6
Q2. Write a C# program to find all odd numbers from a list of integers using LINQ.
Input: numbers = { 1, 2, 3, 4, 5, 6 }
Output: 1, 3, 5
Q3. Write a C# program to sort a list of strings alphabetically using LINQ.
Input: words = { "apple", "banana", "grape", "kiwi" }
Output: apple, banana, grape, kiwi
Q4. Write a C# program to filter a list of numbers greater than 10 using LINQ.
Input: numbers = { 5, 12, 3, 17, 8 }
Output: 12, 17
Q5. Write a C# program to find the first number that is greater than 10 from a list using LINQ.
Input: numbers = { 5, 8, 3, 12, 6 }
Output: 12
Q6. Write a C# program to count how many numbers are greater than 5 in a list using LINQ.
Input: numbers = { 1, 2, 6, 7, 3, 4, 8 }
Output: 4
Q7. Write a C# program to calculate the sum of all numbers in a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 15
Q8. Write a C# program to find the maximum number from a list using LINQ.
Input: numbers = { 2, 3, 1, 6, 8, 4 }
Output: 8
Q9. Write a C# program to find the minimum number from a list using LINQ.
Input: numbers = { 9, 3, 1, 7, 5, 2 }
Output: 1
Q10. Write a C# program to check if all numbers in a list are greater than 0 using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: True
Q11. Write a C# program to check if any number in a list is even using LINQ.
Input: numbers = { 1, 3, 5, 6, 7 }
Output: True
Q12. Write a C# program to group a list of people by their age using LINQ.
Input: people = { new Person("Alice", 25), new Person("Bob", 25), new Person("Charlie", 30) }
Output: 25: Alice, Bob; 30: Charlie
Q13. Write a C# program to find the first three numbers from a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 1, 2, 3
Q14. Write a C# program to create a list of squared numbers from an existing list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 1, 4, 9, 16, 25
Q15. Write a C# program to sort a list of integers in descending order using LINQ.
Input: numbers = { 3, 1, 4, 1, 5, 9 }
Output: 9, 5, 4, 3, 1, 1
Q16. Write a C# program to get distinct elements from a list using LINQ.
Input: numbers = { 1, 2, 3, 1, 2, 4 }
Output: 1, 2, 3, 4
Q17. Write a C# program to join two lists of integers using LINQ.
Input: numbers1 = { 1, 2, 3 }, numbers2 = { 4, 5, 6 }
Output: 1, 2, 3, 4, 5, 6
Q18. Write a C# program to find all words that contain the letter "a" from a list of strings using LINQ.
Input: words = { "apple", "banana", "cherry", "date" }
Output: apple, banana, date
Q19. Write a C# program to remove all negative numbers from a list using LINQ.
Input: numbers = { -1, 2, -3, 4, -5 }
Output: 2, 4
Q20. Write a C# program to select all numbers divisible by 3 from a list using LINQ.
Input: numbers = { 1, 2, 3, 6, 9, 12, 15 }
Output: 3, 6, 9, 12, 15
Q21. Write a C# program to find the average of numbers in a list using LINQ.
Input: numbers = { 5, 10, 15, 20, 25 }
Output: 15
Q22. Write a C# program to check if a list contains a specific number using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }, target = 3
Output: True
Q23. Write a C# program to skip the first 3 numbers in a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 4, 5
Q24. Write a C# program to find the product of all numbers in a list using LINQ.
Input: numbers = { 2, 3, 4 }
Output: 24
Q25. Write a C# program to concatenate all strings from a list into a single string using LINQ.
Input: words = { "Hello", "World" }
Output: HelloWorld
Q26. Write a C# program to sort a list of students by their marks using LINQ.
Input: students = { new Student("Alice", 85), new Student("Bob", 90), new Student("Charlie", 80) }
Output: Bob, Alice, Charlie
Q27. Write a C# program to find the second largest number in a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 4
Q28. Write a C# program to find the unique elements from two lists using LINQ.
Input: list1 = { 1, 2, 3 }, list2 = { 2, 3, 4 }
Output: 1, 4
Q29. Write a C# program to convert a list of strings to uppercase using LINQ.
Input: words = { "apple", "banana", "grape" }
Output: APPLE, BANANA, GRAPE
Q30. Write a C# program to find the intersection of two lists using LINQ.
Input: list1 = { 1, 2, 3 }, list2 = { 2, 3, 4 }
Output: 2, 3
Q31. Write a C# program to select even-indexed elements from a list using LINQ.
Input: numbers = { 10, 20, 30, 40, 50 }
Output: 10, 30, 50
Q32. Write a C# program to group a list of strings by the first letter using LINQ.
Input: words = { "apple", "banana", "cherry", "apricot" }
Output: a: apple, apricot; b: banana; c: cherry
Q33. Write a C# program to find the first word that contains the letter "e" from a list using LINQ.
Input: words = { "apple", "banana", "cherry" }
Output: apple
Q34. Write a C# program to check if any word in a list starts with a capital letter using LINQ.
Input: words = { "apple", "Banana", "cherry" }
Output: True
Q35. Write a C# program to get all students who scored above 80 marks using LINQ.
Input: students = { new Student("Alice", 85), new Student("Bob", 75), new Student("Charlie", 90) }
Output: Alice, Charlie
Q36. Write a C# program to get the average length of strings in a list using LINQ.
Input: words = { "apple", "banana", "cherry" }
Output: 5.33
Q37. Write a C# program to sort a list of numbers in ascending order using LINQ.
Input: numbers = { 5, 2, 9, 1, 6 }
Output: 1, 2, 5, 6, 9
Q38. Write a C# program to find all numbers divisible by both 3 and 5 using LINQ.
Input: numbers = { 3, 5, 15, 30, 7 }
Output: 15, 30
Q39. Write a C# program to find the first word in a list that is longer than 5 characters using LINQ.
Input: words = { "apple", "banana", "grape" }
Output: banana
Q40. Write a C# program to sum up all the even numbers from a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 6
Q41. Write a C# program to find the frequency of each word in a list using LINQ.
Input: words = { "apple", "banana", "apple", "cherry", "banana" }
Output: apple: 2, banana: 2, cherry: 1
Q42. Write a C# program to find the words that are longer than 4 characters using LINQ.
Input: words = { "apple", "cat", "banana", "dog" }
Output: apple, banana
Q43. Write a C# program to find the numbers that are greater than the average in a list using LINQ.
Input: numbers = { 5, 10, 15, 20, 25 }
Output: 15, 20, 25
Q44. Write a C# program to get the last 3 elements of a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5, 6 }
Output: 4, 5, 6
Q45. Write a C# program to remove duplicates from a list of strings using LINQ.
Input: words = { "apple", "banana", "apple", "cherry" }
Output: apple, banana, cherry
Q46. Write a C# program to find all strings that contain the substring "app" using LINQ.
Input: words = { "apple", "banana", "grape", "apricot" }
Output: apple, apricot
Q47. Write a C# program to reverse the order of elements in a list using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 5, 4, 3, 2, 1
Q48. Write a C# program to check if all elements in a list are unique using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: True
Q49. Write a C# program to find the element that appears most frequently in a list using LINQ.
Input: numbers = { 1, 2, 2, 3, 3, 3 }
Output: 3
Q50. Write a C# program to create a new list of squared values of all even numbers using LINQ.
Input: numbers = { 1, 2, 3, 4, 5 }
Output: 4, 16