101个LINQ示例，包含几乎全部操作

Restriction OperatorsWhere - Simple 1public void Linq1() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    var lowNums =        from n in numbers        where n < 5        select n;    Console.WriteLine("Numbers < 5:");    foreach (var x in lowNums) {        Console.WriteLine(x);    }}Where - Simple 2public void Linq2() {    List products = GetProductList();    var soldOutProducts =        from p in products        where p.UnitsInStock == 0        select p;    Console.WriteLine("Sold out products:");    foreach (var product in soldOutProducts) {        Console.WriteLine("{0} is sold out!", product.ProductName);    }}Where - Simple 3public void Linq3() {    List products = GetProductList();    var expensiveInStockProducts =        from p in products        where p.UnitsInStock > 0 && p.UnitPrice > 3.00M        select p;    Console.WriteLine("In-stock products that cost more than 3.00:");    foreach (var product in expensiveInStockProducts) {        Console.WriteLine("{0} is in stock and costs more than 3.00.", product.ProductName);    }}Where - Drilldownpublic void Linq4() {    List customers = GetCustomerList();    var waCustomers =        from c in customers        where c.Region == "WA"        select c;    Console.WriteLine("Customers from Washington and their orders:");    foreach (var customer in waCustomers) {        Console.WriteLine("Customer {0}: {1}", customer.CustomerID, customer.CompanyName);        foreach (var order in customer.Orders) {            Console.WriteLine(" Order {0}: {1}", order.OrderID, order.OrderDate);        }    }}Where - Indexedpublic void Linq5() {    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };    var shortDigits = digits.Where((digit, index) => digit.Length < index);    Console.WriteLine("Short digits:");    foreach (var d in shortDigits) {        Console.WriteLine("The word {0} is shorter than its value.", d);    }}Projection OperatorsSelect - Simple 1public void Linq6() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    var numsPlusOne =        from n in numbers        select n + 1;    Console.WriteLine("Numbers + 1:");    foreach (var i in numsPlusOne) {        Console.WriteLine(i);    }}Select - Simple 2public void Linq7() {    List products = GetProductList();    var productNames =        from p in products        select p.ProductName;    Console.WriteLine("Product Names:");    foreach (var productName in productNames) {        Console.WriteLine(productName);    }}Select - Transformationpublic void Linq8() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    string[] strings = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };    var textNums =         from n in numbers        select strings[n];    Console.WriteLine("Number strings:");    foreach (var s in textNums) {        Console.WriteLine(s);    }         }Select - Anonymous Types 1public void Linq9() {    string[] words = { "aPPLE", "BlUeBeRrY", "cHeRry" };    var upperLowerWords =        from w in words        select new {Upper = w.ToUpper(), Lower = w.ToLower()};    foreach (var ul in upperLowerWords) {        Console.WriteLine("Uppercase: {0}, Lowercase: {1}", ul.Upper, ul.Lower);    }}Select - Anonymous Types 2public void Linq10() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    string[] strings = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };    var digitOddEvens =        from n in numbers        select new {Digit = strings[n], Even = (n % 2 == 0)};    foreach (var d in digitOddEvens) {        Console.WriteLine("The digit {0} is {1}.", d.Digit, d.Even ? "even" : "odd");    }}Select - Anonymous Types 3public void Linq11() {    List products = GetProductList();    var productInfos =        from p in products        select new {p.ProductName, p.Category, Price = p.UnitPrice};    Console.WriteLine("Product Info:");    foreach (var productInfo in productInfos) {        Console.WriteLine("{0} is in the category {1} and costs {2} per unit.", productInfo.ProductName, productInfo.Category, productInfo.Price);    }}Select - Indexedpublic void Linq12() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    var numsInPlace = numbers.Select((num, index) => new {Num = num, InPlace = (num == index)});    Console.WriteLine("Number: In-place?");    foreach (var n in numsInPlace) {        Console.WriteLine("{0}: {1}", n.Num, n.InPlace);    }}Select - Filteredpublic void Linq13() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };    var lowNums =        from n in numbers        where n < 5        select digits[n];    Console.WriteLine("Numbers < 5:");    foreach (var num in lowNums) {        Console.WriteLine(num);    }     }SelectMany - Compound from 1public void Linq14() {    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };    int[] numbersB = { 1, 3, 5, 7, 8 };    var pairs =        from a in numbersA,                b in numbersB        where a < b        select new {a, b};    Console.WriteLine("Pairs where a < b:");    foreach (var pair in pairs) {        Console.WriteLine("{0} is less than {1}", pair.a, pair.b);    }}SelectMany - Compound from 2public void Linq15() {    List customers = GetCustomerList();    var orders =        from c in customers,                o in c.Orders        where o.Total < 500.00M        select new {c.CustomerID, o.OrderID, o.Total};    ObjectDumper.Write(orders);}SelectMany - Compound from 3public void Linq16() {    List customers = GetCustomerList();    var orders =        from c in customers,                o in c.Orders        where o.OrderDate >= new DateTime(1998, 1, 1)        select new {c.CustomerID, o.OrderID, o.OrderDate};    ObjectDumper.Write(orders);}SelectMany - from Assignmentpublic void Linq17() {    List customers = GetCustomerList();    var orders =        from c in customers,                o in c.Orders,                total = o.Total        where total >= 2000.0M        select new {c.CustomerID, o.OrderID, total};    ObjectDumper.Write(orders);}SelectMany - Multiple frompublic void Linq18() {    List customers = GetCustomerList();    DateTime cutoffDate = new DateTime(1997, 1, 1);    var orders =        from c in customers        where c.Region == "WA"        from o in c.Orders        where o.OrderDate >= cutoffDate        select new {c.CustomerID, o.OrderID};    ObjectDumper.Write(orders);}SelectMany - Indexedpublic void Linq19() {    List customers = GetCustomerList();    var customerOrders =        customers.SelectMany(            (cust, custIndex) =>            cust.Orders.Select(o => "Customer #" + (custIndex + 1) +                                    " has an order with OrderID " + o.OrderID) );    ObjectDumper.Write(customerOrders);}Partitioning OperatorsTake - Simplepublic void Linq20() {            int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            var first3Numbers = numbers.Take(3);            Console.WriteLine("First 3 numbers:");            foreach (var n in first3Numbers) {                Console.WriteLine(n);            }        }Take - Nestedpublic void Linq21() {            List<Customer> customers = GetCustomerList();            var first3WAOrders = (                from c in customers                from o in c.Orders                where c.Region == "WA"                select new {c.CustomerID, o.OrderID, o.OrderDate} )                .Take(3);            Console.WriteLine("First 3 orders in WA:");            foreach (var order in first3WAOrders) {                ObjectDumper.Write(order);            }        }Skip - Simplepublic void Linq22() {            int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            var allButFirst4Numbers = numbers.Skip(4);            Console.WriteLine("All but first 4 numbers:");            foreach (var n in allButFirst4Numbers) {                Console.WriteLine(n);            }        }Skip - Nestedpublic void Linq23() {            List<Customer> customers = GetCustomerList();            var waOrders =                from c in customers                from o in c.Orders                where c.Region == "WA"                select new {c.CustomerID, o.OrderID, o.OrderDate};            var allButFirst2Orders = waOrders.Skip(2);            Console.WriteLine("All but first 2 orders in WA:");            foreach (var order in allButFirst2Orders) {                ObjectDumper.Write(order);            }        }TakeWhile - Simplepublic void Linq24() {            int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            var firstNumbersLessThan6 = numbers.TakeWhile(n => n < 6);            Console.WriteLine("First numbers less than 6:");            foreach (var n in firstNumbersLessThan6) {                Console.WriteLine(n);            }        }SkipWhile - Simplepublic void Linq26() {            int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            var allButFirst3Numbers = numbers.SkipWhile(n => n % 3 != 0);            Console.WriteLine("All elements starting from first element divisible by 3:");            foreach (var n in allButFirst3Numbers) {                Console.WriteLine(n);            }        }SkipWhile - Indexedpublic void Linq27() {            int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            var laterNumbers = numbers.SkipWhile((n, index) => n >= index);            Console.WriteLine("All elements starting from first element less than its position:");            foreach (var n in laterNumbers) {                Console.WriteLine(n);            }        }Ordering OperatorsOrderBy - Simple 1publicvoid Linq28() {    string[] words = { "cherry", "apple", "blueberry" };        var sortedWords =        from w in words        orderby w        select w;        Console.WriteLine("The sorted list of words:");    foreach (var w in sortedWords) {        Console.WriteLine(w);    }}OrderBy - Simple 2public void Linq29() {    string[] words = { "cherry", "apple", "blueberry" };    var sortedWords =        from w in words        orderby w.Length        select w;    Console.WriteLine("The sorted list of words (by length):");    foreach (var w in sortedWords) {        Console.WriteLine(w);    }}OrderBy - Simple 3public void Linq30() {    List products = GetProductList();    var sortedProducts =        from p in products        orderby p.ProductName        select p;    ObjectDumper.Write(sortedProducts);}OrderBy - Comparerpublic class CaseInsensitiveComparer : IComparer<string>{    public int Compare(string x, string y)    {        return string.Compare(x, y, true);    }}public void Linq31() {    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry"};    var sortedWords = words.OrderBy(a => a, new CaseInsensitiveComparer());    ObjectDumper.Write(sortedWords);}OrderByDescending - Simple 1public void Linq32() {    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };    var sortedDoubles =        from d in doubles        orderby d descending        select d;    Console.WriteLine("The doubles from highest to lowest:");    foreach (var d in sortedDoubles) {        Console.WriteLine(d);    }}OrderByDescending - Simple 2public void Linq33() {    List products = GetProductList();    var sortedProducts =        from p in products        orderby p.UnitsInStock descending        select p;    ObjectDumper.Write(sortedProducts);}OrderByDescending - Comparerpublic class CaseInsensitiveComparer : IComparerspan class="qs-keyword">string>{    publicint Compare(string x, string y)    {        returnstring.Compare(x, y, true);    }}publicvoid Linq34() {    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry"};        var sortedWords = words.OrderByDescending(a => a, new CaseInsensitiveComparer());            ObjectDumper.Write(sortedWords);}ThenBy - Simplepublicvoid Linq35() {    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };    var sortedDigits =        from d in digits         orderby d.Length, d        select d;    Console.WriteLine("Sorted digits:");    foreach (var d in sortedDigits) {        Console.WriteLine(d);    }}ThenBy - Comparerpublic class CaseInsensitiveComparer : IComparerspan class="qs-keyword">string>{    publicint Compare(string x, string y)    {        returnstring.Compare(x, y, true);    }}publicvoid Linq36() {    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry"};        var sortedWords =        words.OrderBy(a => a.Length)                .ThenBy(a => a, new CaseInsensitiveComparer());            ObjectDumper.Write(sortedWords);}ThenByDescending - Simplepublicvoid Linq37() {    List products = GetProductList();var sortedProducts =        from p in products        orderby p.Category, p.UnitPrice descendingselect p;    ObjectDumper.Write(sortedProducts);}ThenByDescending - Comparerpublic class CaseInsensitiveComparer : IComparerspan class="qs-keyword">string>{    publicint Compare(string x, string y)    {        returnstring.Compare(x, y, true);    }}publicvoid Linq38() {    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry"};        var sortedWords =        words.OrderBy(a => a.Length)                .ThenByDescending(a => a, new CaseInsensitiveComparer());            ObjectDumper.Write(sortedWords);}Reversepublicvoid Linq39() {    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };        var reversedIDigits = (        from d in digits        where d[1] == 'i'        select d)        .Reverse();        Console.WriteLine("A backwards list of the digits with a second character of 'i':");    foreach (var d in reversedIDigits) {        Console.WriteLine(d);    }             }Grouping OperatorsGroupBy - Simple 1public void Linq40() {            int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            var numberGroups =                from n in numbers                group n by n % 5 into g                select new { Remainder = g.Key, Numbers = g };            foreach (var g in numberGroups) {                Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder);                foreach (var n in g.Numbers) {                    Console.WriteLine(n);                }            }}GroupBy - Simple 2public void Linq41() {            string[] words = { "blueberry", "chimpanzee", "abacus", "banana", "apple", "cheese" };            var wordGroups =                from w in words                group w by w[0] into g                select new { FirstLetter = g.Key, Words = g };            foreach (var g in wordGroups) {                Console.WriteLine("Words that start with the letter '{0}':", g.FirstLetter);                foreach (var w in g.Words) {                    Console.WriteLine(w);                }            }        }GroupBy - Simple 3public void Linq42() {            List<Product> products = GetProductList();            var orderGroups =                from p in products                group p by p.Category into g                select new { Category = g.Key, Products = g };            ObjectDumper.Write(orderGroups, 1);        }GroupBy - Nestedpublic void Linq43() {            List<Customer> customers = GetCustomerList();            var customerOrderGroups =                 from c in customers                select                    new {c.CompanyName,                          YearGroups =                             from o in c.Orders                             group o by o.OrderDate.Year into yg                             select                                 new {Year = yg.Key,                                      MonthGroups =                                           from o in yg                                          group o by o.OrderDate.Month into mg                                          select new { Month = mg.Key, Orders = mg }                                     }                        };            ObjectDumper.Write(customerOrderGroups, 3);        }GroupBy - Comparerpublic class AnagramEqualityComparer : IEqualityComparer { public bool Equals(string x, string y) { return getCanonicalString(x) == getCanonicalString(y); } public int GetHashCode(string obj) { return getCanonicalString(obj).GetHashCode(); } private string getCanonicalString(string word) {     char[] wordChars = word.ToCharArray(); Array.Sort(wordChars); return new string(wordChars); } } publicvoid Linq44() { string[] anagrams = {"from ", " salt", " earn ", " last ", " near ", " form "}; var orderGroups = anagrams.GroupBy(w => w.Trim(), new AnagramEqualityComparer()); ObjectDumper.Write(orderGroups, 1); }GroupBy - Comparer, Mappedpublic void Linq45() {            string[] anagrams = {"from ", " salt", " earn ", " last ", " near ", " form "};            var orderGroups = anagrams.GroupBy(                        w => w.Trim(),                         a => a.ToUpper(),                        new AnagramEqualityComparer()                        );            ObjectDumper.Write(orderGroups, 1);        }public class AnagramEqualityComparer : IEqualityComparer<string>        {            public bool Equals(string x, string y) {                return getCanonicalString(x) == getCanonicalString(y);            }            public int GetHashCode(string obj) {                return getCanonicalString(obj).GetHashCode();            }            private string getCanonicalString(string word) {                char[] wordChars = word.ToCharArray();                Array.Sort<char>(wordChars);                return new string(wordChars);            }        }Set OperatorsDistinct - 1publicvoid Linq46() {    int[] factorsOf300 = { 2, 2, 3, 5, 5 };        var uniqueFactors = factorsOf300.Distinct();    Console.WriteLine("Prime factors of 300:");    foreach (var f in uniqueFactors) {        Console.WriteLine(f);    }}Distinct - 2public void Linq47() {    List products = GetProductList();    var categoryNames = (        from p in products        select p.Category)        .Distinct();                                                Console.WriteLine("Category names:");    foreach (var n in categoryNames) {        Console.WriteLine(n);    }}Union - 1publicvoid Linq48() {    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };    int[] numbersB = { 1, 3, 5, 7, 8 };        var uniqueNumbers = numbersA.Union(numbersB);        Console.WriteLine("Unique numbers from both arrays:");    foreach (var n in uniqueNumbers) {        Console.WriteLine(n);    }}Union - 2publicvoid Linq49() {    List products = GetProductList();List customers = GetCustomerList();        var productFirstChars =        from p in products        select p.ProductName[0];    var customerFirstChars =        from c in customers        select c.CompanyName[0];        var uniqueFirstChars = productFirstChars.Union(customerFirstChars);        Console.WriteLine("Unique first letters from Product names and Customer names:");    foreach (var ch in uniqueFirstChars) {        Console.WriteLine(ch);    }}Intersect - 1publicvoid Linq50() {    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };    int[] numbersB = { 1, 3, 5, 7, 8 };        var commonNumbers = numbersA.Intersect(numbersB);        Console.WriteLine("Common numbers shared by both arrays:");    foreach (var n in commonNumbers) {        Console.WriteLine(n);    }}Intersect - 2publicvoid Linq51() {    List products = GetProductList();    List customers = GetCustomerList();        var productFirstChars =        from p in products        select p.ProductName[0];    var customerFirstChars =        from c in customers        select c.CompanyName[0];        var commonFirstChars = productFirstChars.Intersect(customerFirstChars);        Console.WriteLine("Common first letters from Product names and Customer names:");    foreach (var ch in commonFirstChars) {        Console.WriteLine(ch);    }}Except - 1public void Linq52() {    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };    int[] numbersB = { 1, 3, 5, 7, 8 };    IEnumerable<int> aOnlyNumbers = numbersA.Except(numbersB);    Console.WriteLine("Numbers in first array but not second array:");    foreach (var n in aOnlyNumbers) {        Console.WriteLine(n);    }}Except - 2public void Linq53() {    List products = GetProductList();    List customers = GetCustomerList();    var productFirstChars =        from p in products        select p.ProductName[0];    var customerFirstChars =        from c in customers        select c.CompanyName[0];    var productOnlyFirstChars = productFirstChars.Except(customerFirstChars);    Console.WriteLine("First letters from Product names, but not from Customer names:");    foreach (var ch in productOnlyFirstChars) {        Console.WriteLine(ch);    }}Conversion OperatorsTo Arraypublic void Linq54() {    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };    var sortedDoubles =        from d in doubles        orderby d descending        select d;    var doublesArray = sortedDoubles.ToArray();    Console.WriteLine("Every other double from highest to lowest:");    for (int d = 0; d < doublesArray.Length; d += 2) {        Console.WriteLine(doublesArray[d]);    } }To Listpublic void Linq55() {    string[] words = { "cherry", "apple", "blueberry" };    var sortedWords =        from w in words        orderby w        select w;    var wordList = sortedWords.ToList();    Console.WriteLine("The sorted word list:");    foreach (var w in wordList) {        Console.WriteLine(w);    }}To Dictionarypublic void Linq56() {    var scoreRecords = new [] { new {Name = "Alice", Score = 50},                                new {Name = "Bob" , Score = 40},                                new {Name = "Cathy", Score = 45}                              };    var scoreRecordsDict = scoreRecords.ToDictionary(sr => sr.Name);    Console.WriteLine("Bob's score: {0}", scoreRecordsDict["Bob"]);}OfTypepublic void Linq57() {    object[] numbers = { null, 1.0, "two", 3, 4.0f, 5, "six", 7.0 };    var doubles = numbers.OfType<double>();    Console.WriteLine("Numbers stored as doubles:");    foreach (var d in doubles) {        Console.WriteLine(d);    }}Element OperatorsFirst - Simplepublic void Linq58() {    List products = GetProductList();    Product product12 = (        from p in products        where p.ProductID == 12        select p )        .First();    ObjectDumper.Write(product12);}First - Indexedpublic void Linq60() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    int evenNum = numbers.First((num, index) => (num % 2 == 0) && (index % 2 == 0));    Console.WriteLine("{0} is an even number at an even position within the list.", evenNum);}FirstOrDefault - Simplepublic void Linq61() {    int[] numbers = {};    int firstNumOrDefault = numbers.FirstOrDefault();    Console.WriteLine(firstNumOrDefault);}FirstOrDefault - Conditionpublic void Linq62() {    List products = GetProductList();    Product product789 = products.FirstOrDefault(p => p.ProductID == 789);    Console.WriteLine("Product 789 exists: {0}", product789 != null);}FirstOrDefault - Indexedpublic void Linq63() {    double?[] doubles = { 1.7, 2.3, 4.1, 1.9, 2.9 };    double? num = doubles.FirstOrDefault((n, index) => (n >= index - 0.5 && n <= index + 0.5));    if (num != null)        Console.WriteLine("The value {1} is within 0.5 of its index position.", num);    else        Console.WriteLine("There is no number within 0.5 of its index position.", num);}ElementAtpublic void Linq64() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    int fourthLowNum = (        from n in numbers        where n < 5        select n )        .ElementAt(3); // 3 because sequences use 0-based indexing    Console.WriteLine("Fourth number < 5: {0}", fourthLowNum);}Generation OperatorsRangepublic void Linq65() {    var numbers =       from n in Sequence.Range(100, 50)       selectnew {Number = n, OddEven = n % 2 == 1 ? "odd" : "even"};    foreach (var n in numbers) {       Console.WriteLine("The number {0} is {1}.", n.Number, n.OddEven);    } }Repeatpublic void Linq66() {    var numbers = Sequence.Repeat(7, 10);    foreach (var n in numbers) {       Console.WriteLine(n);    } }QuantifiersAny - Simplepublic void Linq67() {    string[] words = { "believe", "relief", "receipt", "field" };    bool iAfterE = words.Any(w => w.Contains("ei"));    Console.WriteLine("There is a word that contains in the list that contains 'ei': {0}", iAfterE); }Any - Indexedpublic void Linq68() {    int[] numbers = { -9, -4, -8, -3, -5, -2, -1, -6, -7 };    bool negativeMatch = numbers.Any((n, index) => n == -index);    Console.WriteLine("There is a number that is the negative of its index: {0}", negativeMatch); }Any - Groupedpublic void Linq69() {    List products = GetProductList();   var productGroups =       from p in products       group p by p.Category into g       where g.Group.Any(p => p.UnitsInStock == 0)       select new {Category = g.Key, Products = g.Group};    ObjectDumper.Write(productGroups, 1); }All - Simplepublic void Linq70() {    int[] numbers = { 1, 11, 3, 19, 41, 65, 19 };   bool onlyOdd = numbers.All(n => n % 2 == 1);   Console.WriteLine("The list contains only odd numbers: {0}", onlyOdd); }All - Indexedpublic void Linq71() {    int[] lowNumbers = { 1, 11, 3, 19, 41, 65, 19 };    int[] highNumbers = { 7, 19, 42, 22, 45, 79, 24 };    bool allLower = lowNumbers.All((num, index) => num < highNumbers[index]);    Console.WriteLine("Each number in the first list is lower than its counterpart in the second list: {0}", allLower); }All - Groupedpublic void Linq72() {    List products = GetProductList();   var productGroups =       from p in products       group p by p.Category into g       where g.Group.All(p => p.UnitsInStock > 0)       select new {Category = g.Key, Products = g.Group};    ObjectDumper.Write(productGroups, 1); }Aggregate OperatorsCount - Simplepublic void Linq73() {    int[] factorsOf300 = { 2, 2, 3, 5, 5 };    int uniqueFactors = factorsOf300.Distinct().Count();    Console.WriteLine("There are {0} unique factors of 300.", uniqueFactors); }Count - Conditionalpublic void Linq74() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    int oddNumbers = numbers.Count(n => n % 2 == 1);    Console.WriteLine("There are {0} odd numbers in the list.", oddNumbers); }Count - Indexedpublic void Linq75() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };   int oddEvenMatches = numbers.Count((n, index) => n % 2 == index % 2);   Console.WriteLine("There are {0} numbers in the list whose odd/even status " +         "matches that of their position.", oddEvenMatches); }Count - Nestedpublic void Linq76() {    List customers = GetCustomerList();   var orderCounts =       from c in customers       select new {c.CustomerID, OrderCount = c.Orders.Count()};   ObjectDumper.Write(orderCounts); }Count - Groupedpublic void Linq77() {    List products = GetProductList();   var categoryCounts =       from p in products       group p by p.Category into g       select new {Category = g.Key, ProductCount = g.Group.Count()};   ObjectDumper.Write(categoryCounts); }Sum - Simplepublic void Linq78() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    double numSum = numbers.Sum();    Console.WriteLine("The sum of the numbers is {0}.", numSum); }Sum - Projectionpublic void Linq79() {   string[] words = { "cherry", "apple", "blueberry" };   double totalChars = words.Sum(w => w.Length);   Console.WriteLine("There are a total of {0} characters in these words.", totalChars); }Sum - Groupedpublic void Linq80() {    List products = GetProductList();   var categories =       from p in products       group p by p.Category into g       select new {Category = g.Key, TotalUnitsInStock = g.Group.Sum(p => p.UnitsInStock)};    ObjectDumper.Write(categories); }Min - Simplepublic void Linq81() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    int minNum = numbers.Min();    Console.WriteLine("The minimum number is {0}.", minNum); }Min - Projectionpublic void Linq82() {    string[] words = { "cherry", "apple", "blueberry" };    int shortestWord = words.Min(w => w.Length);    Console.WriteLine("The shortest word is {0} characters long.", shortestWord); }Min - Groupedpublic void Linq83() {    List products = GetProductList();   var categories =       from p in products       group p by p.Category into g       select new {Category = g.Key, CheapestPrice = g.Group.Min(p => p.UnitPrice)};    ObjectDumper.Write(categories); }Min - Elementspublic void Linq84() {    List products = GetProductList();   var categories =       from p in products       group p by p.Category into g       from minPrice = g.Group.Min(p => p.UnitPrice)       select new {Category = g.Key, CheapestProducts = g.Group.Where(p => p.UnitPrice == minPrice)};   ObjectDumper.Write(categories, 1); }Max - Simplepublic void Linq85() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };   int maxNum = numbers.Max();    Console.WriteLine("The maximum number is {0}.", maxNum); }Max - Projectionpublic void Linq86() {    string[] words = { "cherry", "apple", "blueberry" };    int longestLength = words.Max(w => w.Length);    Console.WriteLine("The longest word is {0} characters long.", longestLength); }Max - Groupedpublic void Linq87() {    List products = GetProductList();   var categories =       from p in products       group p by p.Category into g       select new {Category = g.Key, MostExpensivePrice = g.Group.Max(p => p.UnitPrice)};    ObjectDumper.Write(categories); }Max - Elementspublic void Linq88() {    List products = GetProductList();   var categories =       from p in products       group p by p.Category into g       from maxPrice = g.Group.Max(p => p.UnitPrice)       select new {Category = g.Key, MostExpensiveProducts = g.Group.Where(p => p.UnitPrice == maxPrice)};    ObjectDumper.Write(categories, 1); }Average - Simplepublic void Linq89() {    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    double averageNum = numbers.Average();    Console.WriteLine("The average number is {0}.", averageNum); }Average - Projectionpublic void Linq90() {    string[] words = { "cherry", "apple", "blueberry" };    double averageLength = words.Average(w => w.Length);    Console.WriteLine("The average word length is {0} characters.", averageLength); }Average - Groupedpublic void Linq91() {    List products = GetProductList();   var categories =       from p in products       group p by p.Category into g       select new {Category = g.Key, AveragePrice = g.Group.Average(p => p.UnitPrice)};    ObjectDumper.Write(categories); }Fold - Simplepublic void Linq92() {    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };    double product = doubles.Fold((runningProduct, nextFactor) => runningProduct * nextFactor);    Console.WriteLine("Total product of all numbers: {0}", product); }Fold - Seedpublic void Linq93() {    double startBalance = 100.0;    int[] attemptedWithdrawals = { 20, 10, 40, 50, 10, 70, 30 };    double endBalance =       attemptedWithdrawals.Fold(startBalance,          (balance, nextWithdrawal) =>             ( (nextWithdrawal <= balance) ? (balance - nextWithdrawal) : balance ) );    Console.WriteLine("Ending balance: {0}", endBalance); }Miscellaneous OperatorsConcat - 1public void Linq94() {    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };    int[] numbersB = { 1, 3, 5, 7, 8 };    var allNumbers = numbersA.Concat(numbersB);    Console.WriteLine("All numbers from both arrays:");    foreach (var n in allNumbers) {        Console.WriteLine(n);    }}Concat - 2public void Linq95() {    List customers = GetCustomerList();    List products = GetProductList();    var customerNames =        from c in customers        select c.CompanyName;    var productNames =        from p in products        select p.ProductName;    var allNames = customerNames.Concat(productNames);    Console.WriteLine("Customer and product names:");    foreach (var n in allNames) {        Console.WriteLine(n);    }}EqualAll - 1public void Linq96() {    var wordsA = new string[] { "cherry", "apple", "blueberry" };    var wordsB = new string[] { "cherry", "apple", "blueberry" };    bool match = wordsA.EqualAll(wordsB);    Console.WriteLine("The sequences match: {0}", match);}EqualAll - 2public void Linq97() {    var wordsA = new string[] { "cherry", "apple", "blueberry" };    var wordsB = new string[] { "apple", "blueberry", "cherry" };    bool match = wordsA.EqualAll(wordsB);    Console.WriteLine("The sequences match: {0}", match);}Custom Sequence OperatorsCombinepublic static class CustomSequenceOperators{    public static IEnumerable Combine(this IEnumerable first, IEnumerable second, Func func) {        using (IEnumerator e1 = first.GetEnumerator(), e2 = second.GetEnumerator()) {            while (e1.MoveNext() && e2.MoveNext()) {                yield return func(e1.Current, e2.Current);            }        }    }}public void Linq98() {                int[] vectorA = { 0, 2, 4, 5, 6 };    int[] vectorB = { 1, 3, 5, 7, 8 };    int dotProduct = vectorA.Combine(vectorB, (a, b) => a * b).Sum();    Console.WriteLine("Dot product: {0}", dotProduct);}Query ExecutionDeferredpublic void Linq99() {    // Sequence operators form first-class queries that    // are not executed until you enumerate over them.    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    int i = 0;    var q =        from n in numbers        select ++i;    // Note, the local variable 'i' is not incremented    // until each element is evaluated (as a side-effect):    foreach (var v in q) {        Console.WriteLine("v = {0}, i = {1}", v, i);             } }Immediatepublic void Linq100() {    // Methods like ToList() cause the query to be    // executed immediately, caching the results.    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };            int i = 0;    var q = (        from n in numbers        select ++i )        .ToList();    // The local variable i has already been fully    // incremented before we iterate the results:    foreach (var v in q) {        Console.WriteLine("v = {0}, i = {1}", v, i);    } }Query Reusepublic void Linq101() {    // Deferred execution lets us define a query once    // and then reuse it later after data changes.    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };    var lowNumbers =        from n in numbers        where n <= 3        select n;    Console.WriteLine("First run numbers <= 3:");    foreach (int n in lowNumbers) {        Console.WriteLine(n);    }    for (int i = 0; i < 10; i++) {        numbers[i] = -numbers[i];    }    // During this second run, the same query object,    // lowNumbers, will be iterating over the new state    // of numbers[], producing different results:    Console.WriteLine("Second run numbers <= 3:");    foreach (int n in lowNumbers) {        Console.WriteLine(n);    }}