如何使用linq查询LIST

Question

假设我将人类实例添加到列表然后我需要使用linq查询列表.

List lst=new List();
lst.add(new person{ID=1,Name="jhon",salaty=2500});
lst.add(new person{ID=2,Name="Sena",salaty=1500});
lst.add(new person{ID=3,Name="Max",salaty=5500});
lst.add(new person{ID=4,Name="Gen",salaty=3500});

现在我想用linq查询上面的列表.请指导我的示例代码.

Answer 1

我还建议使用LinqPad作为一种方便的方法来解决Linq对于高级和初学者的问题.

例:

Answer 2

好吧,你给出的代码开头是无效的 - List是泛型类型,它有一个Add方法而不是add等等.

但你可以这样做:

List<Person> list = new List<Person>
{
    new person{ID=1,Name="jhon",salaty=2500},
    new person{ID=2,Name="Sena",salaty=1500},
    new person{ID=3,Name="Max",salaty=5500}.
    new person{ID=4,Name="Gen",salaty=3500}
};

// The "Where" LINQ operator filters a sequence
var highEarners = list.Where(p => p.salaty > 3000);

foreach (var person in highEarners)
{
    Console.WriteLine(person.Name);
}

如果您想了解所有LINQ运算符的详细信息,以及如何在LINQ to Objects中实现它们,您可能会对我的Edulinq博客系列感兴趣.

Answer 3

var persons = new List<Person>
    {
        new Person {ID = 1, Name = "jhon", Salary = 2500},
        new Person {ID = 2, Name = "Sena", Salary = 1500},
        new Person {ID = 3, Name = "Max", Salary = 5500},
        new Person {ID = 4, Name = "Gen", Salary = 3500}
    };

var acertainperson = persons.Where(p => p.Name == "jhon").First();
Console.WriteLine("{0}: {1} points",
    acertainperson.Name, acertainperson.Salary);

jhon: 2500 points

var doingprettywell = persons.Where(p => p.Salary > 2000);
            foreach (var person in doingprettywell)
            {
                Console.WriteLine("{0}: {1} points",
                    person.Name, person.Salary);
            }

jhon: 2500 points
Max: 5500 points
Gen: 3500 points

        var astupidcalc = from p in persons
                          where p.ID > 2
                          select new
                                     {
                                         Name = p.Name,
                                         Bobos = p.Salary*p.ID,
                                         Bobotype = "bobos"
                                     };
        foreach (var person in astupidcalc)
        {
            Console.WriteLine("{0}: {1} {2}",
                person.Name, person.Bobos, person.Bobotype);
        }

Max: 16500 bobos
Gen: 14000 bobos

Answer 4

因为你没有给任何指示,以什么你想要的,这里是所有使用不同的方法,LINQ LINQ 101个样本的链接:101个LINQ示例

此外,您应该真正真正将您更改List为强类型列表(List<T>),并正确定义T,并将T的实例添加到列表中.它将真正使查询更容易,因为您不必一直抛出所有内容.