static void Main()
{
int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
string[] conStrings = { "서울특별시", "대전", "수원시", "부산", "섬" };
// Aggregate Functions
Console.WriteLine(numbers.Min());
Console.WriteLine(numbers.Where(x => x % 2 == 0).Min());
Console.WriteLine(numbers.Max());
Console.WriteLine(numbers.Sum());
Console.WriteLine(numbers.Count(x => x % 2 == 0));
Console.WriteLine(numbers.Average());
Console.WriteLine(numbers.Aggregate((a, b) => a * b));
Console.WriteLine(Enumerable.Range(1, 10).Aggregate((a, b) => a + b));
Enumerable.Repeat("Hello", 10).ToList().ForEach(x => Console.WriteLine(x));
Console.WriteLine("-----------------------------------");
Console.WriteLine(conStrings.Min(x => x.Length));
Console.WriteLine(conStrings.First(x => x.Length == 2).ToString());
Console.WriteLine(conStrings.OrderByDescending(s => s).First(s => s.Contains("시")).ToString());
Console.WriteLine(conStrings.Aggregate((a, b) => a + ", " + b));
conStrings.ToList().Where(x => x.Contains("시")).ToList()
.ForEach(c => Console.WriteLine(c.ToString()));
Console.WriteLine("-----------------------------------");
// Restriction Operators
var result = numbers.ToList()
.Select((num, index) => new { Numbers = num, Index = index })
.Where(x => x.Numbers % 2 != 0); //.Select(x => x.Index);
foreach (var item in result)
{
Console.WriteLine($"{item} : {item.Numbers} {item.Index}");
}
var resultEmp = Employee.GetAllEmployees()
.Where(x => x.Salary >= 2000)
.Select(e => new { e.ID, e.Name, e.Gender, MonthlySalary = e.Salary / 12 });
foreach (var item in resultEmp)
{
Console.WriteLine($"{item.ID} {item.Name} {item.Gender} {item.MonthlySalary}");
}
Console.WriteLine("-----------------------------------");
// SelectMany Operator
string[] stringArray = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "0123456789" };
var resultChar = stringArray.SelectMany(s => s);
foreach (var c in resultChar)
{
Console.WriteLine(c);
}
// var sj = from student in Student.GetAllStudents()
// from subject in student.Subjects
// select subject;
var subjects = Student.GetAllStudents().SelectMany(s => s.Subjects).Distinct();
foreach (var item in subjects)
{
Console.WriteLine($"{item}");
}
var subjects1 = Student.GetAllStudents()
.SelectMany(s => s.Subjects, (student, subject) => new { StudentName = student.Name, SubjectName = subject });
foreach (var item in subjects1)
{
Console.WriteLine($"{item.StudentName} {item.SubjectName}");
}
Console.WriteLine("-----------------------------------");
// Ordering Operators
var r = Employee.GetAllEmployees()
.OrderByDescending(s => s.Name)
.OrderBy(s => s.Gender)
.ThenBy(s => s.Salary)
.Reverse();
foreach (var student in r)
{
Console.WriteLine(student.Name);
}
Console.WriteLine("-----------------------------------");
// Partitioning Operators
var c1 = conStrings.Take(3);
foreach (var i in c1) Console.WriteLine("c1: " + i);
var c2 = conStrings.Skip(3);
foreach (var i in c2) Console.WriteLine("c2: " + i);
var c3 = conStrings.TakeWhile(s => s.Length >= 2);
foreach (var i in c3) Console.WriteLine("c3: " + i);
var c4 = conStrings.SkipWhile(s => s.Length > 2);
foreach (var i in c4) Console.WriteLine("c4: " + i);
// pagiing
//students.Skip((pageNumber - 1) * pageSize).Take(pageSize)
Console.WriteLine("-----------------------------------");
// Cast and OfType operators
// ToList:Cast, ToArray:OfType, ToDictionary:AsEnumerable, ToLookup:AsQueryable
ArrayList list = new ArrayList { 1, 2, 3, "ABC", "DEF" };
IEnumerable<int> r1 = list.OfType<int>();
foreach (int i in r1) Console.WriteLine(i);
Console.WriteLine("-----------------------------------");
// GroupBy
var empGroup = Employee.GetAllEmployees().GroupBy(x => x.Gender);
foreach (var i in empGroup)
{
Console.WriteLine(i.Key + " c: " + i.Count());
Console.WriteLine(i.Key + " x: " + i.Count(x => x.Gender == "M"));
Console.WriteLine(i.Key + " m: " + i.Max(x => x.Salary));
Console.WriteLine(i.Key + " s: " + i.Sum(x => x.Salary));
}
Console.WriteLine("-----------------------------------");
// Group by multiple
var e1 = Employee.GetAllEmployees()
.GroupBy(x => new { x.Department, x.Gender })
.OrderBy(g => g.Key.Department).ThenBy(g => g.Key.Gender)
.Select(g => new
{
Dept = g.Key.Department,
g.Key.Gender,
Employees = g.OrderBy(x => x.Name)
});
foreach (var i in e1)
Console.WriteLine(i.Dept + "/" + i.Gender + "/" + i.Employees.Count());
Console.WriteLine("-----------------------------------");
// Element Operations
int[] num = { };
//Console.WriteLine(num.First());
Console.WriteLine(num.FirstOrDefault());
Console.WriteLine(numbers.First(x => x % 2 == 0));
Console.WriteLine(numbers.ElementAt(1));
Console.WriteLine(numbers.Where(x => x == 1).Single()); //Single:sequence
var r2 = num.DefaultIfEmpty(100);
foreach (var i in r2) Console.WriteLine(i);
Console.WriteLine("-----------------------------------");
// Group Join
// var query = dept.Join(emp, d => d.DeptNO, e => e.Department.DeptNO, (d, e) =>
// new {d.DeptNO, d.DeptName, e.EmpNO, e.EmpName});
/*
var result = Employee.GetAllEmployees()
.GroupJoin(Department.GetAllDepartments(),
e => e.DepartmnetID
d => d.ID,
(emp, depts) => new {emp, depts})
.SelectMany(z => z.depts.DefaultIfEmpty(),
(a, b) => new
{
EmployeeName = a.emp.Name,
DepartmentName = b == null ? "No Department" : b.Name
}
*/
// Set operators
string[] con = { "KR", "kr", "KO", "KO", "ko" };
con.Distinct().ToList().ForEach(x => Console.WriteLine(x));
Console.WriteLine("-----------------------------------");
con.Distinct(StringComparer.OrdinalIgnoreCase).ToList().ForEach(x => Console.WriteLine(x));
int[] num1 = { 1, 2, 3, 7 };
int[] num2 = { 4, 5, 6, 7 };
num1.Concat(num2).ToList().ForEach(x => Console.WriteLine(x));
Console.WriteLine("-----------------------------------");
num1.Union(num2).ToList().ForEach(x => Console.WriteLine(x));
Console.WriteLine("-----------------------------------");
num1.Intersect(num2).ToList().ForEach(x => Console.WriteLine(x));
Console.WriteLine("-----------------------------------");
num1.Except(num2).ToList().ForEach(x => Console.WriteLine(x));
// SequenceEqual Operator
string[] con1 = {"ABC", "DF"};
string[] con2 = {"abc", "df"};
Console.WriteLine(con1.SequenceEqual(con2).ToString());
Console.WriteLine(con1.SequenceEqual(con2, StringComparer.OrdinalIgnoreCase).ToString());
}