The function pointer is used to store the reference of the method. The pointer is similar to delegate in C#, but it has some differences from the delegate.

Difference between function pointer and delegate:

Function pointer Delegate
1.Function pointer should have return type except “void” 1. Delegate can have any return type.
2. It has capable to hold one function reference at a time. 2. It can hold multiple method reference at time.
3. The pointer method should has at least one argument 3. It is not necessary to has any arguments.

Syntax of Function Pointer:

  1. public delegate TResult Func<[in T,…], out TResult>(
  2. T arg
  3. )
We can pass any number of parameters in Function pointer. It is optional, but we should have the non-void return type.

Example:
  1. class Program
  2. {
  3. static Func<string,string> FunctionPTR = null;
  4. static Func<string,string, string> FunctionPTR1 = null;
  6. static string Display(string message)
  7. {
  8. Console.WriteLine(message);
  9. return null;
  10. }
  12. static string Display(string message1,string message2)
  13. {
  14. Console.WriteLine(message1);
  15. Console.WriteLine(message2);
  16. return null;
  17. }
  18. static void Main(string[] args)
  19. {
  20. FunctionPTR = Display;
  21. FunctionPTR1= Display;
  22. FunctionPTR("Welcome to function pointer sample.");
  23. FunctionPTR1("Welcome","This is function pointer sample");
  24. Console.ReadKey();
  25. }
  26. }