功能和行动
Func 为参数化匿名函数提供了持有者。前导类型是输入,最后一种类型始终是返回值。
// square a number.
Func<double, double> square = (x) => { return x * x; };
// get the square root.
// note how the signature matches the built in method.
Func<double, double> squareroot = Math.Sqrt;
// provide your workings.
Func<double, double, string> workings = (x, y) =>
string.Format("The square of {0} is {1}.", x, square(y))
Action 对象类似于 void 方法,因此它们只有一个输入类型。没有结果放在评估堆栈上。
// right-angled triangle.
class Triangle
{
public double a;
public double b;
public double h;
}
// Pythagorean theorem.
Action<Triangle> pythagoras = (x) =>
x.h = squareroot(square(x.a) + square(x.b));
Triangle t = new Triangle { a = 3, b = 4 };
pythagoras(t);
Console.WriteLine(t.h); // 5.