LINQ

OfType: select a certain type

Posted on by coder 
   
 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass {
    public static void Main() {
        object[] numbers = { null, 1.0, "two", 3, 4.0f, 5, "six", 7.0 };
        var doubles = numbers.OfType<double>();
        Console.WriteLine("Numbers stored as doubles:");
        foreach (var d in doubles) {
            Console.WriteLine(d);
        }
    }
}

Query a list of objects by its property

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Reflection;
using System.Linq;
using System.Xml;
using System.Xml.Linq;
class Employee {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Role {
    int _id;
    string role;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public string Role {
        get { return role; }
        set { role = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Employee> people = new List<Employee> {
               new Employee { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Employee { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}
            };

        List<Role> roles = new List<Role> {
              new Role  { ID = 1, Role = "Manager" },
              new Role  { ID = 2, Role = "Developer" }
            };


        var query = people
                    .Where(p => p.ID == 1)
                    .Select(p => new { p.FirstName, p.LastName });
    }
}

Query by Person's FirstName

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Reflection;

class Person {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Person> people = new List<Person> {
               new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"},
               new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"},
               new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"}
            };

        var query = from p in people
                    where p.FirstName == "B"
                    select p;

    }
}

Select object in a List

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Reflection;

class Person {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Person> people = new List<Person> {
               new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"},
               new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"},
               new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"}
            };
        var query = from p in people select p;
    }
}

Query an array of object by its property value

Posted on by coder 
   
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Drawing;
public class Book {
    public String Title { get; set; }

    public override String ToString() {
        return Title;
    }
}

class Program {
    static void Main(string[] args) {
        Book[] books = {
      new Book { Title="A" },
      new Book { Title="F" },
      new Book { Title="E" } };

        var titles =
          books
            .Where(book => book.Title.Contains("A"))
            .Select(book => book.Title);

    }
}