namespace LambdaDemo
{
class Person
{
public string Name {
get;
set; }
public int Age {
get;
set; }
}
internal static class Program
{
static void Main(
string[] args)
{
List<Person> persons =
GetPersonList();
persons = persons.Where(p => p.Age >
6).ToList();
Person personP = persons.SingleOrDefault(p => p.Age ==
2);
List<Person> personsC = persons.Where(p => p.Name.Contains(
"儿子")).ToList();
ExpressionMethod();
}
private static List<Person>
GetPersonList()
{
List<Person> plist =
new List<Person>
();
for (
int i =
0; i <
7; i++
)
{
plist.Add(new Person {Name =
"儿子", Age =
8 -
i});
}
return plist;
}
// 表达式树
private static void ExpressionMethod()
{
//计算 a*b+c*d的值
ParameterExpression a = Expression.Parameter(
typeof (
int),
"a");
ParameterExpression b = Expression.Parameter(
typeof (
int),
"b");
BinaryExpression ab =
Expression.Multiply(a, b);
ParameterExpression c = Expression.Parameter(
typeof (
int),
"c");
ParameterExpression d = Expression.Parameter(
typeof (
int),
"d");
BinaryExpression cd =
Expression.Multiply(c, d);
BinaryExpression abcd =
Expression.Add(ab, cd);
Expression<Func<
int,
int,
int,
int,
int>> lam = Expression.Lambda<Func<
int,
int,
int,
int,
int>>
(abcd, a, b,
c, d);
Console.WriteLine(lam +
"");
Func<
int,
int,
int,
int,
int> f =
lam.Compile();
Console.WriteLine(f(2,
1,
5,
1) +
"");
Console.ReadKey();
}
}
}
转载于:https://www.cnblogs.com/FangZhaohu/p/5069445.html
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