除了上面提到的集合类型外,还有其他几个要掌握的集合类型,它们是在实际应用中发展而来的对以上基础类型的扩展:SortedList<T>、SortedDictionary<TKey, TValue>、Sorted-Set<T>。它们所扩展的对应类分别为List<T>、Dictionary<TKey, TValue>、HashSet<T>,作用是将原本无序排列的元素变为有序排列。 除了排序上的...
//方式一//分成key-value的数组string[] id = list.Select(a =>a.id.ToString()).ToArray();//dt是datatable类型的,执行LINQ语句,这里的.AsEnumerable()是延迟发生,不会立即执行,实际上什么都没有发生string[] id = dt.AsEnumerable().Select(a => a.Field<int>("id").ToString()).ToArray();/...
若要缓存卡片组,可以利用 LINQ 方法ToArray和ToList;将它们追加到查询时,它们将执行你告诉查询的相同作,但现在它们会将结果存储在数组或列表中,具体取决于你选择调用的方法。 将 LINQ 方法ToArray追加到查询并再次运行程序: C# publicstaticvoidMain(string[] args){ IEnumerable<Suit>? suits = Suits(); IEnumer...
XElement xelement = XElement.Load("Employees.xml");varels =fromelinxelement.Elements("Employee")whereel.Element("Sex").Value =="男"selectel;foreach(XElement iteminels) {stringid = item.Element("EmpId").Value;stringname = item.Element("Name").Value; Console.WriteLine($"id:{id},姓名:...
您可以使用 LINQ 來查詢任何可列舉的集合,例如 List<T>、Array或Dictionary<TKey,TValue>。 集合可以是使用者定義或 .NET API 所傳回的類型。 在 LINQ 方法論中,您可以撰寫宣告式程式碼來描述您想要擷取的資料。 LINQ to Objects 提供使用 LINQ 進行程式設計的絕佳簡介。 LINQ 查詢比傳統 foreach 迴圈提供三...
ToString(), id = i, salary = i * 1000, family = new List<UserInfo> { new UserInfo { name = "username's family" + i.ToString(), id = i, salary = i * 1000-100 } } } ); } var valid_salarys = from user in users from u in user.family where user.salary>1000 && u....
largeCitiesList = (fromcountryincountriesfromcityincountry.Citieswherecity.Population >10000selectcity ).ToList();// or split the expressionIEnumerable<City> largeCitiesQuery =fromcountryincountriesfromcityincountry.Citieswherecity.Population >10000selectcity;varlargeCitiesList2 = largeCitiesQuery.ToList(...
' Obtain a list of customers.DimcustomersAsList(OfCustomer) = GetCustomers()' Return customers that are grouped based on country.Dimcountries =FromcustIncustomersOrderBycust.Country, cust.CityGroupByCountryName = cust.CountryIntoCustomersInCountry =Group, Count()OrderByCountryName' Output the result...
{// Print the key value of the IGrouping.Console.WriteLine(packageGroup.Key);// Iterate through each value in the// IGrouping and print its value.foreach(stringstrinpackageGroup) Console.WriteLine(" {0}", str); } }/* This code produces the following output: C Coho Vineyard 89453312 Con...
value.// Select Company appended to TrackingNumber for each element value in the Lookup.Lookup<char,string> lookup = (Lookup<char,string>)packages.ToLookup(p => p.Company[0], p => p.Company +" "+ p.TrackingNumber);// Iterate through each IGrouping in the Lookup and output the ...