Overloading a method in subclass (Enum vs int)

Question

Why the following two code samples produce different output? Case 1 ``` enum EnumType { First, Second, Third } class ClassB { public string Func(int index) { return "Func(int)"; } public string Func(EnumType type) { return "Func(EnumType)"; } } class Program { static void Main(string[] args) { ClassB b = new ClassB(); Console.WriteLine(b.Func(0)); Console.WriteLine(b.Func(EnumType.First)); Console.ReadLine(); } } ``` Output: ``` Func(int) Func(EnumType) ``` Case 2 ``` enum EnumType { First, Second, Third } class ClassA { public string Func(int index) { return "Func(int)"; } } class ClassB : ClassA { public string Func(EnumType enumType) { return "Func(EnumType)"; } } class Program { static void Main(string[] args) { ClassB b = new ClassB(); Console.WriteLine(b.Func(0)); Console.WriteLine(b.Func(EnumType.First)); Console.ReadLine(); } } ``` Output: ``` Func(EnumType) Func(EnumType) ``` I am puzzled. Does it mean that Func(EnumType) hides Func(int) declared in the base? If this is the c…

Accepted Answer

Yes, it does hide the Func(int) declared in class A.

Furthermore, please see enum (C# Reference)

The default underlying type of enumeration elements is int

You might also want to have a look at Polymorphism (C# Programming Guide)

EDIT

If you ere to change

```
Console.WriteLine(b.Func(0));          
Console.WriteLine(b.Func(1)); 
Console.WriteLine(b.Func(EnumType.First)); 
```

to

```
int i = 0;
Console.WriteLine(b.Func(i));          
Console.WriteLine(b.Func(1)); 
Console.WriteLine(b.Func(EnumType.First)); 
```

you will find that the output should be

```
Func(int)   
Func(int)   
Func(EnumType)
```

It would seem that 0 is implicitly casted to the default enum value if passed directly to the function call.

EDIT 2

I checked the IL code and it does seem that it implicitly casts the 0 to an enum

```
IL_0000: nop
IL_0001: newobj instance void ClassB::.ctor()
IL_0006: stloc.0
IL_0007: ldloc.0
IL_0008: ldc.i4.0
IL_0009: callvirt instance string ClassB::Func(valuetype EnumType)
IL_000e: call void [mscorlib]System.Console::WriteLine(string)
IL_0013: nop
IL_0014: ldloc.0
IL_0015: ldc.i4.0
IL_0016: callvirt instance string ClassB::Func(valuetype EnumType)
IL_001b: call void [mscorlib]System.Console::WriteLine(string)
IL_0020: nop
IL_0021: call string [mscorlib]System.Console::ReadLine()
IL_0026: pop
IL_0027: ret
```

Overloading a method in subclass (Enum vs int)

Solution

Problem

Related problems