Ch10.md

Chapter 10 Examples

Examples from Chapter 10 (LINQ) of Programming C# 8.0 (O'Reilly).

Query Expressions

• Example 1. A LINQ query expression
• Example 2. The non-LINQ equivalent
• Example 3. Extracting just one property in a query
• Example 4. The effect of a query expression
• Example 5. How trivial select clauses expand
• Example 6. Query with a let clause
• Example 7. How multivariable query expressions expand (approximately)
• Example 8. Nonsensical Where and Select
• Example 9. A meaningless query
• Example 10. How the compiler transforms the meaningless query
• Example 11. A custom LINQ provider for CultureInfo[]

Deferred Evaluation

• Example 12. Query with an infinite source sequence
• Example 13. A custom deferred Where operator
• Example 14. Accidental reevaluation of a deferred query

LINQ, Generics, and IQueryable<T>

• Example 15. IQueryable and IQueryable<T>
• Example 16. Enumerable versus Queryable

Standard LINQ Operators

• Example 17. Sample input data for LINQ queries

Filtering

• Example 18. Where operator with index
• Example 19. The OfType<T> operator

Select

• Example 20. Select operator with index
• Example 21. Indexed Select downstream of Where operator
• Example 22. Indexed Select upstream of Where operator
• Example 23. Fetching more data than is needed
• Example 24. A select clause with an anonymous type
• Example 25. Using Select to transform numbers

SelectMany

• Example 26. Using SelectMany from a query expression
• Example 27. SelectMany operator
• Example 28. Flattening a jagged array
• Example 29. SelectMany without item projection
• Example 30. One implementation of SelectMany

Ordering

• Example 31. Query expression with orderby clause
• Example 32. How not to apply multiple ordering criteria
• Example 33. Multiple ordering criteria in a query expression
• Example 34. Multiple ordering criteria with LINQ operators

Specific Items and Subranges

• Example 35. Applying the Single operator to a query
• Example 36. Single operator with predicate
• Example 37. Using First to select the longest course
• Example 38. How not to use ElementAt

Aggregation

• Example 39. Average operator with projection
• Example 40. Max with projection
• Example 41. Sum and equivalent with Aggregate
• Example 42. Implementing Max with Aggregate
• Example 43. Implementing Average with Aggregate
• Example 44. Aggregating bounding boxes
• Example 45. More verbose and less obscure bounding box aggregation
• Example 46. The effect of Aggregate

Set Operations

• Example 47. Removing duplicates with Distinct

Whole-Sequence, Order-Preserving Operations

• Example 48. Combining lists with Zip

Grouping

• Example 49. Grouping query expression
• Example 50. Expanding a simple grouping query
• Example 51. Group query with item projection
• Example 52. Expanding a group query with an item projection
• Example 53. Group query with group projection
• Example 54. Expanded group query with group projection
• Example 55. GroupBy with key and group projections
• Example 56. GroupBy operator with key, item, and group projections
• Example 57. Composite group key

Joins

• Example 58. Class associating a student with a course
• Example 59. Query with join clause
• Example 60. Using the Join operator directly
• Example 61. A grouped join
• Example 62. GroupJoin operator

Conversion

• Example 63. How not to cast a sequence
• Example 64. How to cast a sequence
• Example 65. Creating a lookup