The Unity move - converting application from C++ to C#

I can't speak to the quality of any specific converter but some of the differences I've noticed from my experience so far (please correct me if any of these are inaccurate):

array declirations:

float[] f;

instead of:

float f[];

No fixed size arrays:

float[] f = new float[4];

instead of:

float f[4];

no stack variables:

func( new Vector3(0, 0, 0) );

instead of:

func( Vector3(0, 0, 0) );

Also, strings are very different. I'm not sure if you're using std::string, char*, or a custom class regardless it will probably be different.

I have a similar problem. May i need to convert all my C++ source code on C# or is there a way to avoid that. I have checked the P/Invoke method,(To communicate with my C++ code) but it's not allowed on WebPlayer. Iam considering checking if with an ActivX plug-in it could work...

So any feedback would be great... Thanks

• C# has support for pointers, but you aren't allowed to use them in safe code (pointers are regarded as unsafe).

• All class type objects are reference objects. Reference objects are allocated on heap and copied by reference. There is also stackalloc keyword but I doubt you can use it in Unity3D.

• All struct type objects are value objects. Value objects are allocated on the stack and of course are sent copy-by-value to methods.

• String is immutable.

In case you want to rather pass the reference of a value to a method, use the ref keyword (& in C++)

void Bar() { int i = 0; Bar(ref i); }

void Foo(ref int value) { value += 42; }

You can also use the out keyword if you want to explicitly set a value through reference.

void Bar() { int i = 0; Bar(out i); }

void Foo(out int value) { value = 42; }

varargs are done with params keyword.

void Foobar() { int sum = Sum(5, 3, 1, 4, 6, 2, 4); }

int Sum(params int[] values) { int result = 0; for(int i = 0; i < values.Length; ++i) { result += values[i]; } }

Arrays are defined as such:

int[] integers; // null by default

Arrays are created as such:

integers = new int[size]; // all elements are default(int) which is 0.

Or put together if you want:

int[] integers = new int[42];

Arrays can also be inline populated:

int[] integers = { 4, 5, 6, 2, 4, 1 };

Member variables can be initialized in their definition:

class Foo
{
    int Bar = 42;
    float Bar2 = 42.0f;
}

Member variables can be set in an initialization list:

Foo foo = new Foo()
{
   Bar = 4,
   Bar2 = 2.0f
};

Generics in C# are not the same as templates in C++ and not near as flexible. Use of generics require you define the interface before hand. This also means you only can pass in types that are derived from Component:

void Foo<T>(T value) where T : Component
{
    value.name = "Bar";
}

Also you can't derive from generic types. This won't work for example:

class CppExample<T> : T { }

However, this will, since you can't have a type parameters as base classes but you can have base classes that accept type parameters:

class CSharpExample<T> : SomeBaseClass<T> { }

Oh I don't remember much about structs in C++ but I think you could derive from them in C++. In C# you can't derive from a struct.

Also all types access modifier is internal by default (meaning only the assembly (dll/exe) can access it). All member variables are private by default. There is also a fifth modifier called protected internal meaning the assembly or any derived object has access to the member.

And I guess you could go on with some differences and gotchas but I ran out of time :)