Can a class have two methods with the same name but different in parameters called?

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• Question

• In Ruby, you can have two methods with the same name and same set of parameters. When executed, the recent version is compiled and executed.

  How C# handles this? Can I have two similar methods in C#?

Answers

• In Ruby, classes are never closed, and you can extend a class with new methods. If a method happens to have the same signature as an already existing method, the method will be replaced.

  C# does not allow this. Although you can define partial classes in C#, the compiler handles them differently from Ruby: all the parts of the class are first collected into the final class, and then compiled. If you have two parts that both define the same method with the same signature, you will get a compilation error ("Type 'Foo' already defines a member called 'Bar' with the same parameter types").

  The difference is, that in Ruby, the extension is done at runtime, while in C#, the parts are collected at compile time. If you want to mimic something like the Ruby functionality, you could look at the Strategy pattern, for instance, which allows you to extend the functionality of your class at runtime.

  ---

  Hey, look! This system allows signatures of more than 60 cha

  • Marked as answer by Wednesday, August 22, 2012 1:20 AM

• So this means, C# doesn't support method versioning.

  What do you call method versioning?

  If you mean changing the behavior of an inherited method, that's done by overriding the method: you write the method in the derived class and add the 'override' modifier.

  If you mean modifying a method dynamically, you can use a delegate field or property as though it was a method, and assign a different method to it at runtime:

  class ModifiableClass
  {
      public Func SomeMethod { get; set; }
      public ModifiableClass()
      {
          SomeMethod = (int x) =>
          {
              return 2 * x;
          };
      }
  }
  class Program
  {
      public static void Main()
      {
          ModifiableClass c = new ModifiableClass();
          Console.WriteLine("SomeMethod doubles the value: " + c.SomeMethod(42));
          c.SomeMethod = (int x) =>
          {
              return 3 * x;
          };
          Console.WriteLine("SomeMethod now triples the value: " + c.SomeMethod(42));
      }
  }

  If you mean adding a method to an object which doesn't have it to start with, you need dynamic objects:

  class Program
  {
      public static void Main()
      {
          dynamic e = new ExpandoObject();
          e.SomeMethod = (int i) =>
              {
                  Console.WriteLine("The value is {i}", i);
              };
          e.SomeMethod(42);
      }
  }

  
  
  • Marked as answer by Lisa Zhu Wednesday, August 22, 2012 1:21 AM

• You can have two similar methods in c# but the arguments should be different.

  • Marked as answer by Lisa Zhu Wednesday, August 22, 2012 1:20 AM

• Short Answer: No.

  You can't have two methods with the same name and the same parameters. The compiler wouldn't know which Method to use if you call it.

  You didn't specify your problem, but maybe one of this two soultions can help you:

  First, Overloading a Method (I'm sure you know of this). The names of the methods are the same, but they got a different parameter list.

  Second, Named and Optional parameters (maybe even in combination with overloading). For more on this topic, read here.

  I hope this useful to you.

  Regards,

  Steve.

  • Marked as answer by Lisa Zhu Wednesday, August 22, 2012 1:20 AM

1. Different ways to overload the method
2. By changing the no. of arguments
3. By changing the datatype
4. Why method overloading is not possible by changing the return type
5. Can we overload the main method
6. method overloading with Type Promotion

If a class has multiple methods having same name but different in parameters, it is known as Method Overloading.

If we have to perform only one operation, having same name of the methods increases the readability of the program.

Suppose you have to perform addition of the given numbers but there can be any number of arguments, if you write the method such as a(int,int) for two parameters, and b(int,int,int) for three parameters then it may be difficult for you as well as other programmers to understand the behavior of the method because its name differs.

So, we perform method overloading to figure out the program quickly.

Advantage of method overloading

Method overloading increases the readability of the program.

Different ways to overload the method

There are two ways to overload the method in java

1. By changing number of arguments
2. By changing the data type

In Java, Method Overloading is not possible by changing the return type of the method only.

1) Method Overloading: changing no. of arguments

In this example, we have created two methods, first add() method performs addition of two numbers and second add method performs addition of three numbers.

In this example, we are creating static methods so that we don't need to create instance for calling methods.

Output:

2) Method Overloading: changing data type of arguments

In this example, we have created two methods that differs in data type. The first add method receives two integer arguments and second add method receives two double arguments.

Output:

Q) Why Method Overloading is not possible by changing the return type of method only?

In java, method overloading is not possible by changing the return type of the method only because of ambiguity. Let's see how ambiguity may occur:

Output:

Compile Time Error: method add(int,int) is already defined in class Adder

System.out.println(Adder.add(11,11)); //Here, how can java determine which sum() method should be called?

Note: Compile Time Error is better than Run Time Error. So, java compiler renders compiler time error if you declare the same method having same parameters.

Can we overload java main() method?

Yes, by method overloading. You can have any number of main methods in a class by method overloading. But JVM calls main() method which receives string array as arguments only. Let's see the simple example:

Output:

Method Overloading and Type Promotion

One type is promoted to another implicitly if no matching datatype is found. Let's understand the concept by the figure given below:

As displayed in the above diagram, byte can be promoted to short, int, long, float or double. The short datatype can be promoted to int, long, float or double. The char datatype can be promoted to int,long,float or double and so on.

Example of Method Overloading with TypePromotion

Example of Method Overloading with Type Promotion if matching found

If there are matching type arguments in the method, type promotion is not performed.

Output:int arg method invoked

Example of Method Overloading with Type Promotion in case of ambiguity

If there are no matching type arguments in the method, and each method promotes similar number of arguments, there will be ambiguity.

Output:Compile Time Error
       

One type is not de-promoted implicitly for example double cannot be depromoted to any type implicitly.

Can we have same method name with different parameters?

When methods have the same name but different parameters it's called?

Can a class have 2 methods with same name?

What happens if two methods have same name?