LINQ101例子

LINQ - Set Operators
Distinct去掉重复 Union&＃xff08;合并&＃xff09; Intersect&＃xff08;交集&＃xff09; Except叉集 Concat&＃xff08;连接&＃xff09;

LINQ - Restriction Operators
<> &＃61;&＃61; && ||

LINQ - Query Execution
i&＃43;&＃43;

LINQ - Quantifiers
Any集合中是否有元素满足某一条件 All集合中所有元素是否都满足某一条件
Contains集合中是否包含有某一元素 Exists是否存在

LINQ - Projection Operators
dt.AsEnumerable()可用于linq方法 n.Field(column)

LINQ - Partitioning Operators
Take(3)前3个 Skip(4) 跳过前4个 TakeWhile(n &＃61;> n <6)不要后面6个 SkipWhile&＃xff08;&＃xff09;指定条件跳过

LINQ - Ordering Operators
orderby word orderby word.Length orderby d descending倒叙 words.OrderBy&＃xff08;&＃xff09;
words.OrderByDescending&＃xff08;&＃xff09; orderby digit.Length, digit
words.OrderBy(a &＃61;> a.Length).ThenBy(a &＃61;> a, new CaseInsensitiveComparer());
words.OrderBy(a &＃61;> a.Length).ThenByDescending(a &＃61;> a, new CaseInsensitiveComparer());
.Reverse()翻转
public class CaseInsensitiveComparer : IComparer
{
public int Compare(string x, string y)
{
return string.Compare(x, y, StringComparison.OrdinalIgnoreCase);
}
}

LINQ - Miscellaneous Operators
Concat 连接 wordsA.SequenceEqual(wordsB);比较 是否相同

LINQ - Join Operators
join cust in customers on new { sup.City, sup.Country } equals new { cust.City, cust.Country
} into cs

LINQ - Generation Operators
var numbers &＃61;from n in Enumerable.Range(100, 50) 生成指定范围的整数数列
var numbers &＃61; Enumerable.Repeat(7, 10); 生成重复的序列号

LINQ - Element Operators
.First(); First(s &＃61;> s[0] &＃61;&＃61; &＃39;o&＃39;); FirstOrDefault();
FirstOrDefault(p &＃61;> p.ProductID &＃61;&＃61; 789); ElementAt(1); 返回索引指定

LINQ - Custom Sequence Operators
public static IEnumerable Combine(this IEnumerable first,
IEnumerable second, System.Func func)
{
using (IEnumerator e1 &＃61; first.GetEnumerator(), e2 &＃61;
second.GetEnumerator())
{
while (e1.MoveNext() && e2.MoveNext())
{
yield return func(e1.Current, e2.Current);
}
}
}