LINQ |连接运算符|连接
原文:https://www . geesforgeks . org/linq-concation-operator-concat/
串联是将一个序列附加到另一个序列中的过程。在 LINQ，连接操作只包含一个称为 Concat 的运算符。它用于追加两个相同类型的序列或集合，并返回一个新的序列或集合。
- 它不支持 C# 和 VB.NET 语言中的查询语法。
- 它支持 C# 和 VB.NET 语言中方法语法。
- 它同时出现在可查询类和可枚举类中。
- 它通过使用延迟执行来实现。
- 它允许重复元素。
如下图所示，这里两个相同类型的序列连接成一个序列。
例 1:
// C# program to concatenate the
// given sequences
using System;
using System.Linq;
class GFG {
static public void Main()
{
// Data source
char[] sequence1 = {'p', 'q', 'r', 's', 'y', 'z'};
char[] sequence2 = {'p', 'm', 'o', 'e', 'c', 'z'};
// Display the sequences
Console.WriteLine("Sequence 1 is: ");
foreach(var s1 in sequence1)
{
Console.WriteLine(s1);
}
Console.WriteLine("Sequence 2 is: ");
foreach(var s2 in sequence2)
{
Console.WriteLine(s2);
}
// Concatenate the given array
// Using Concat function
var result = sequence1.Concat(sequence2);
Console.WriteLine("New Sequence:");
foreach(var val in result)
{
Console.WriteLine(val);
}
}
}
Output:
Sequence 1 is:
p
q
r
s
y
z
Sequence 2 is:
p
m
o
e
c
z
New Sequence:
p
q
r
s
y
z
p
m
o
e
c
z
例 2:
// C# program to print the major
// language of the employees
using System;
using System.Linq;
using System.Collections.Generic;
// Employee details
public class Employee1 {
public int emp_id1
{
get;
set;
}
public string emp_name1
{
get;
set;
}
public string emp_lang1
{
get;
set;
}
}
// Employee details
public class Employee2 {
public int emp_id2
{
get;
set;
}
public string emp_name2
{
get;
set;
}
public string emp_lang2
{
get;
set;
}
}
class GFG {
// Main method
static public void Main()
{
List<Employee1> emp1 = new List<Employee1>() {
new Employee1() {emp_id1 = 209, emp_name1 = "Anjita",
emp_lang1 = "C#"},
new Employee1() {emp_id1 = 210, emp_name1 = "Soniya",
emp_lang1 = "C"},
new Employee1() {emp_id1 = 211, emp_name1 = "Rohit",
emp_lang1 = "Java"},
};
List<Employee2> emp2 = new List<Employee2>() {
new Employee2() {emp_id2 = 219, emp_name2 = "Anita",
emp_lang2 = "Scala"},
new Employee2() {emp_id2 = 223, emp_name2 = "Manya",
emp_lang2 = "Python"},
new Employee2() {emp_id2 = 266, emp_name2 = "Rohan",
emp_lang2 = "Ruby"},
};
// Query to concatenate the major
// languages of the employees of
// two different departments
// Using Concat method
var res = emp1.Select(e => e.emp_lang1).Concat(emp2.Select(e => e.emp_lang2));
Console.WriteLine("Major Languages Used are: ");
foreach(var val in res)
{
Console.WriteLine(val);
}
}
}
Output:
Major Languages Used are:
C#
C
Java
Scala
Python
Ruby
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