Linq检查一个列表中的项目是否在另一个列表中 [英] Linq to check if item in one list is in another list

问题描述

我知道在传统代码中它将是另一个foreach循环中的foreach循环。 有一个很好的例子，或者用传统的代码方法可以做得更好吗？

TIA

Harry

解决方案

你好，

看看使用
Any

< pre class ="prettyprint"style =""> [TestMethod]
public void MyTestMethod（）
{
var firstList = new List< string>（）{" Mazda"，"福特"，"雪佛兰"，"α"};
var secondList = new List< string>（）{" Volkswagen"，""""""""      };

var result = secondList.Any（car => car ==" Ford"）;
Assert.IsTrue（result）;
}

由于福特位于第一个列表中，因此上述Assert返回true。

使用类列表的示例  ;

公共类公司
 {
 public int Id {get;组; } 
 public string Name {get;组; } 
公共字符串FirstName {get;组; } 
公共字符串LastName {get;组; } 
 public string Title {get;组; } 
公共覆盖字符串ToString（）
 {
 return 

" {Id}，'{Name}'" ;;
}
}

 [TestMethod] 
 public void MyTestMethod（）
 {
 var customer1 = new Company（）{FirstName =" Karen"，LastName =" Payne" ;}; 
 var customer2 = new Company（）{FirstName =" Mary"，LastName =" Jackson"}; 
 var customer3 = new Company（）{FirstName =" Bill"，LastName =" Adams"}; 
 
 var cust1 = new List< Company>（）{customer1，customer2，customer3}; 
 var cust2 = new List< Company>（）{customer1，customer2}; 
 
 Assert.IsTrue（cust2.Any（cust => cust.FirstName ==" Karen"&& cust.LastName ==" Payne"））; 
 
 cust2.RemoveAt（0）; 
 Assert.IsFalse（cust2.Any（cust => cust.FirstName ==" Karen"&& cust.LastName ==" Payne"））; 
} 

I know in conventional code it would be a foreach loop within another foreach loop.  Is there a good example of this or is this something better accomplished with the conventional code method?

TIA

Harry

解决方案

Hello,

Look at using Any

[TestMethod]
public void MyTestMethod()
{
    var firstList = new List<string>() {"Mazda","Ford","Chevy","Alpha"};
    var secondList = new List<string>() { "Volkswagen", "Ford", "BMW", "Daimler" };

    var result = secondList.Any(car => car == "Ford");
    Assert.IsTrue(result);
} 

The above Assert returns true since Ford is in the first list.

Example using a list for a class 

public class Company
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Title { get; set; }
    public override string ToString()
    {
        return

"{Id}, '{Name}'"; } }

[TestMethod]
public void MyTestMethod()
{
    var customer1 = new Company() {FirstName = "Karen", LastName = "Payne"};
    var customer2 = new Company() {FirstName = "Mary", LastName = "Jackson"};
    var customer3 = new Company() {FirstName = "Bill", LastName = "Adams"};

    var cust1 = new List<Company>() {customer1,customer2,customer3};
    var cust2 = new List<Company>() {customer1,customer2};

    Assert.IsTrue(cust2.Any(cust => cust.FirstName == "Karen" && cust.LastName == "Payne"));

    cust2.RemoveAt(0);
    Assert.IsFalse(cust2.Any(cust => cust.FirstName == "Karen" && cust.LastName == "Payne"));
} 

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