Ch10.md

Chapter 10 Examples

Examples from Chapter 10 (LINQ) of Programming C# 12.0 (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)

Deferred Evaluation

• Example 8. Query with an infinite source sequence
• Example 9. A custom deferred Where operator
• Example 10. Accidental reevaluation of a deferred query

LINQ, Generics, and IQueryable<T>

• Example 11. IQueryable and IQueryable<T>
• Example 12. Enumerable versus Queryable

Standard LINQ Operators

• Example 13. Sample input data for LINQ queries

Filtering

• Example 14. Where operator with index
• Example 15. The OfType<T> operator
• Example 16. Removing duplicates with Distinct

Select

• Example 17. Select operator with index
• Example 18. Indexed Select downstream of Where operator
• Example 19. Indexed Select upstream of Where operator
• Example 20. Fetching more data than is needed
• Example 21. A select clause with an anonymous type
• Example 22. Using Select to transform numbers

SelectMany

• Example 23. Using SelectMany from a query expression
• Example 24. SelectMany operator
• Example 25. Flattening a jagged array
• Example 26. SelectMany without item projection
• Example 27. One implementation of SelectMany

Ordering

• Example 28. Query expression with orderby clause
• Example 29. How not to apply multiple ordering criteria
• Example 30. Multiple ordering criteria in a query expression
• Example 31. Multiple ordering criteria with LINQ operators

Specific Items and Subranges

• Example 32. Applying the Single operator to a query
• Example 33. Single operator with predicate
• Example 34. Using First to select the longest course
• Example 35. SingleOrDefault with explicit default value
• Example 36. How not to use ElementAt

Aggregation

• Example 37. Average operator with projection
• Example 38. Max with projection
• Example 39. MaxBy with projection for criteria but not for result
• Example 40. MaxBy with projection for criteria but not for result with error on empty input
• 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

Grouping

• Example 47. Grouping query expression
• Example 48. Expanding a simple grouping query
• Example 49. Group query with item projection
• Example 50. Expanding a group query with an item projection
• Example 51. Group query with group projection
• Example 52. Expanded group query with group projection
• Example 53. GroupBy with key and group projections
• Example 54. GroupBy operator with key, item, and group projections
• Example 55. Composite group key

Conversion

• Example 56. How not to cast a sequence
• Example 57. How to cast a sequence
• Example 58. Creating a lookup