表达式树使用(一)

万物只要有开始，就必有结束

Program.cs

class Program
{
static void Main(string[] args)
{

Expression<Func<int, int, int>> expression = (a, b) => a + b;
Console.WriteLine("这是表达式主体{0}", expression.Body);
Console.WriteLine("这是实际表达式{0}", expression);
//int d = expression(3, 5);
Func<int, int, int> function = (a, b) => a + b;
Func<int, int, bool> function2 = (a,b) => (a < b);

Expression<Func<int, int, bool>> Expression2 = (a, b) => (a < b);
Console.WriteLine("这是expression2的主体{0}", Expression2.Body);
Expression<Func<int, bool>> lessThan = i => i < 5;
Console.WriteLine(lessThan);
Console.WriteLine("表达式的结果{0}  ", lessThan);
Expression<Func<int, int>> plusEquals = (a) =>  (a+a);
Console.WriteLine("这是plusEqual的主体{0}", plusEquals.Body);
Console.WriteLine(plusEquals);
//Int32 c = plusEquals(3);
int c = plusEquals.Compile()(3);
Console.WriteLine("这里是plusEquals表达式的结果{0}", c);
//我想在这里做一个sql查询
//var query = from cus in db.Customers where cus.City == "Nantes" select new { cus.City, cus.CompanyName };

Console.ReadLine();
}
}

运行结果如图: