The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.
How to: Iterate Over a User-Defined Collection with for each
Visual Studio 2015
The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.
The latest version of this topic can be found at How to: Iterate Over a User-Defined Collection with for each.
For a class to be a managed collection, it needs a non-private GetEnumerator function that returns a handle to an Enumerator class or an interface. An enumerator class must contain the declaration for non-static MoveNext function and Current property.
Simple user defined collection with reference types.
// for_each_user_defined_collections.cpp
// compile with: /clr
using namespace System;
public interface struct IMyEnumerator {
bool MoveNext();
property Object^ Current {
Object^ get();
}
void Reset();
};
public ref struct MyArray {
MyArray( array<int>^ d ) {
data = d;
}
ref struct enumerator : IMyEnumerator {
enumerator( MyArray^ myArr ) {
colInst = myArr;
currentIndex = -1;
}
virtual bool MoveNext() {
if( currentIndex < colInst->data->Length - 1 ) {
currentIndex++;
return true;
}
return false;
}
property Object^ Current {
virtual Object^ get() {
return colInst->data[currentIndex];
}
};
virtual void Reset() {}
~enumerator() {}
MyArray^ colInst;
int currentIndex;
};
array<int>^ data;
IMyEnumerator^ GetEnumerator() {
return gcnew enumerator(this);
}
};
int main() {
int retval = 0;
MyArray^ col = gcnew MyArray( gcnew array<int>{10, 20, 30 } );
for each ( Object^ c in col )
retval += (int)c;
retval -= 10 + 20 + 30;
for each ( int c in gcnew MyArray( gcnew array<int>{10, 20, 30 } ) )
retval += c;
retval -= 10 + 20 + 30;
Console::WriteLine("Return Code: {0}", retval );
return retval;
}
Return Code: 0
Show: