static List <int> MyFindAll(MyPredicate2 mp2)
{
int numToFind = 20;
List <int> list = new List <int>();
foreach (int x in array)
{
if (mp2(numToFind, x))
{
list.Add(x);
}
}
return(list);
}
static void Main(string[] args)
{
PreloadArray();
Display(array);
// find the first value that is positive
MyPredicate predicate = IsPositive;
int firstPosX = Find(predicate); // compiler creates a delegate to be passed to the Find() method
Console.WriteLine($"\n\nFirst positive value: { firstPosX }.");
// find the first value that is negative
predicate = IsNegative;
int firstNegX = Find(predicate);
Console.WriteLine($"\n\nFirst negative value: { firstNegX }.");
// find the first value that is negative and odd
predicate = IsNegativeOdd;
int firstNegOddX = Find(predicate);
Console.WriteLine($"\n\nFirst negative odd value: { firstNegOddX }.");
// find the first value that is positive and even
predicate = IsPositiveEven;
int firstPosEvenX = Find(predicate);
Console.WriteLine($"\n\nFirst positive even value: { firstPosEvenX }.");
// another way to do this: pass a delegate referencing a lambda expression
MyPredicate predicate2 = x => (x) > 0 && x % 2 != 0; // boolean expression for 'positive' 'odd'
int firstPositiveOdd = Find(predicate2);
Console.WriteLine($"\n\nFirst positive odd value (Lambda-style): { firstPositiveOdd }.");
// Create an example using a Delegate that takes two int parameters and returns bool
// then wire-up the Delegate to a method that collects all matching instances of x
// return the count of matches
MyPredicate2 mp2 = AreEqual;
List <int> matches = MyFindAll(mp2);
Console.WriteLine($"\n\nNumber of matching items found: { matches.Count }.");
Console.WriteLine("\n\nPress <Enter> to exit. . .");
Console.ReadLine();
}
public Form1()
{
InitializeComponent();
//1: Create a delegate object to a named method
//d1 = new MyPredicate(IsEvenPositive);
//Or use a short-cut syntax
d1 = IsEvenPositive;
//2: Create a delegate to an anonymous method
d2 = delegate(int x)
{
return(x > 0 && x % 2 == 0);
};
//3: Create a delegate to a lambda expression
d3 = x => x > 0 && x % 2 == 0;
d4 = (x, y) => x > 0 && x % 2 == 1 && y >= Math.Pow(x, 2);
d5 = (a, b) => (a.Average() + b.Average() / 2);
}
