1、使用委托、lambda表达式、linq等知识完成以下内容：(本题35分)
（1）要求定义employee类，带有name属性（string类型），带有birthday属性（datetime类型），带有salary属性（double类型）；重载tostring()方法，将信息以适当格式输出。[8分]
（2）定义一个委托如下 ：
delegate bool employeepredicate(employee emp);
写一个静态方法findemployee，根据filter参数在数组中查找符合条件的person实例，方法声明为：[6分]
static list
findemployee(employee[] emps, employeepredicate t) （3）写一个静态方法filterbysalary，使之符合委托employeepredicate定义，当salary超过7000时返回true。[3分]
（4）在主方法中添加代码，结合（2）和（3），将工资超过7000的员工找出来并打印。[3分]
（5）编写一个静态类myextensions，其中有一个静态方法eighties，扩展datetime类型的功能。如日期符合“80后”定义则返回true，否则返回false。其中年份数据可通过 datetime的year属性访问到。[5分]
private static bool iseighties(datetime dt) （6）利用（5）中扩展方法写一个lambda表达式，调用（2）中方法，把80后员工找出来并打印。[5分]
（7）利用linq技术，把80后员工找出来，按工资从高到低排序，并打印。[5分]
主方法中已提供以下代码和数据：
public static void main(string[] argv){employee[] employees = new employee[] {new employee { name = "damon", birthday = new datetime(1988, 5, 1), salary = 4000 },new employee { name = "niki", birthday = new datetime(1995, 10, 4), salary = 7500 },new employee { name= "ayrton", birthday = new datetime(1982, 6, 23), salary = 9200 },new employee { name= "graham", birthday = new datetime(1994, 9, 15), salary = 6800 }};}
2、array类的静态sort方法要求数组中的元素是可比较的。[16分]
1）扩展第1题中employee类的功能，使之实现泛型icomparable接口（其中定义了方法int compareto(t p)），按salary进行比较。(第1题中已答出的代码不需要重复写。)[4分]
2）如果需要以其它方式对employee对象进行排序，就需要自己创建一个类employeecomparer，实现泛型icomparer接口（其中定义了方法int compare(t a, t b)），它独立于要比较的类，因此需要两个参数进行比较。
写个一employeecomparer类，继承icomparer，内部包含一个整型sort属性。当sort为0时按salary进行比较，为1时按name排序，为2时按datetime排序。其中string类和datetime类均已实现icomparable接口。[8分]
3）在主方法中实现按salary和name的两种排序。[4分]
using system;
using system.collections.generic;
using system.linq;namespace homework20
{/**1、使用委托、lambda表达式、linq等知识完成以下内容：(本题35分)（1）要求定义employee类，带有name属性（string类型），带有birthday属性（datetime类型），带有salary属性（double类型）；重载tostring()方法，将信息以适当格式输出。[8分]（2）定义一个委托如下 ：delegate bool employeepredicate(employee emp);写一个静态方法findemployee，根据filter参数在数组中查找符合条件的person实例，方法声明为：[6分]static list findemployee(employee[] emps, employeepredicate t)（3）写一个静态方法filterbysalary，使之符合委托employeepredicate定义，当salary超过7000时返回true。[3分]（4）在主方法中添加代码，结合（2）和（3），将工资超过7000的员工找出来并打印。[3分]（5）编写一个静态类myextensions，其中有一个静态方法eighties，扩展datetime类型的功能。如日期符合“80后”定义则返回true，否则返回false。其中年份数据可通过 datetime的year属性访问到。[5分]private static bool iseighties(datetime dt)（6）利用（5）中扩展方法写一个lambda表达式，调用（2）中方法，把80后员工找出来并打印。[5分]（7）利用linq技术，把80后员工找出来，按工资从高到低排序，并打印。[5分]主方法中已提供以下代码和数据：public static void main(string[] argv){employee[] employees = new employee[] {new employee { name = "damon", birthday = new datetime(1988, 5, 1), salary = 4000 },new employee { name = "niki", birthday = new datetime(1995, 10, 4), salary = 7500 },new employee { name= "ayrton", birthday = new datetime(1982, 6, 23), salary = 9200 },new employee { name= "graham", birthday = new datetime(1994, 9, 15), salary = 6800 }};}*//**2、array类的静态sort方法要求数组中的元素是可比较的。[16分]1）扩展第1题中employee类的功能，使之实现泛型icomparable接口（其中定义了方法int compareto(t p)），按salary进行比较。(第1题中已答出的代码不需要重复写。)[4分]2）如果需要以其它方式对employee对象进行排序，就需要自己创建一个类employeecomparer，实现泛型icomparer接口（其中定义了方法int compare(t a, t b)），它独立于要比较的类，因此需要两个参数进行比较。写个一employeecomparer类，继承icomparer，内部包含一个整型sort属性。当sort为0时按salary进行比较，为1时按name排序，为2时按datetime排序。其中string类和datetime类均已实现icomparable接口。[8分]3）在主方法中实现按salary和name的两种排序。[4分]*/class employee : icomparable{public string name;public datetime birthday;public double salary;public override string tostring(){return string.format("{0}: salary={1}, birthday={2}", name, salary, birthday);}public int compareto(employee emp){return (int)(salary - emp.salary);}}public static class myextensions{public static bool iseighties(this datetime d){return d.year > 1979 && d.year < 1990;}}class employeecomparer : icomparer{public int sort { get; set; }public employeecomparer(int sort){sort = sort;}public int compare(employee e1, employee e2){switch (sort){case 0:return (int)(e1.salary - e1.salary);case 1:return e1.name.compareto(e2.name);default:return e1.birthday.compareto(e2.birthday);}}}class program{delegate bool employeepredicate(employee emp);static list findemployee(employee[] emps, employeepredicate t) {list results = new list();foreach (employee p in emps){if (t(p))results.add(p);}return results;}private static bool filterbysalary(employee emp) {return emp.salary > 7000;}public static void main(string[] args){employee[] employees = new employee[] {new employee { name = "damon", birthday = new datetime(1988, 5, 1), salary = 4000 },new employee { name = "niki", birthday = new datetime(1995, 10, 4), salary = 7500 },new employee { name= "ayrton", birthday = new datetime(1982, 6, 23), salary = 9200 },new employee { name= "graham", birthday = new datetime(1994, 9, 15), salary = 6800 }};list high = findemployee(employees, filterbysalary);foreach (employee emp in high)console.writeline(emp);list eighties = findemployee(employees, p => p.birthday.iseighties());foreach (employee emp in eighties)console.writeline(emp);var eighties2 = from emp in employeeswhere emp.birthday.iseighties() == trueorderby emp.salary descendingselect emp;foreach (employee emp in eighties2)console.writeline(emp);array.sort(employees);foreach (employee emp in employees)console.writeline(emp);array.sort(employees,new employeecomparer(1));foreach (employee emp in employees)console.writeline(emp);console.writeline("hello world!");}}
}
//1、
//(1)class employee{public string name { get; set; }public datetime birthday { get; set; }public double salary { get; set; }public override string tostring(){return string.format("{0}: salary={1}, birthday={2}", name, salary, birthday);}}
//(2)private static list findemployee(employee[] ps, employeepredicate t){list results = new list();foreach (employee p in ps){if (t(p))results.add(p);}return results;}
//(3)private static bool filterbysalary(employee emp){return emp.salary >= 7000;}
//(4)list high = findemployee(employees, filterbysalary);foreach(employee emp in high)console.writeline(emp);
//(5)public static class myextensions{public static bool iseighties(this datetime d){return d.year > 1979 && d.year < 1980;}}
//(6)list eighties = findemployee(employees, p => p.birthday.iseighties());foreach(employee emp in eighties)console.writeline(emp);
//(7)var eighties2 = from emp in employeeswhere emp.birthday.iseighties() == trueorderby emp.salary descendingselect emp;foreach (employee emp in eighties2)console.writeline(emp);
//2、class employee : icomparable{public string name { get; set; }public datetime birthday { get; set; }public double salary { get; set; }public override string tostring(){return string.format("{0}: salary={1}, birthday={2}", name, salary, birthday);}public int compareto(employee emp){return (int)(salary - emp.salary);}}class employeecomparer : icomparer{public int sort { get; set; }public employeecomparer(int sort){sort = sort;}public int compare(employee e1, employee e2){switch(sort){case 0:return (int)(e1.salary - e1.salary);case 1:return e1.name.compareto(e2.name);default:return e1.birthday.compareto(e2.birthday);}}}
https://www.cnblogs.com/skm-blog/p/4229487.html
https://www.cnblogs.com/forever-ys/p/10315830.html
总结
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