Is Int32^ i = gcnew Int32() allocated on managed heap?

Question

Basically I would like to know the difference between
Int32^ i = gcnew Int32();
and
Int32* i2 = new Int32();

I have written the following code:

#include <stdio.h>
#using <mscorlib.dll>

using namespace System;

int main(void) {

    Int32^ i = gcnew Int32();
    Int32* i2 = new Int32();

    printf("%p %d\n", i2, *i2);
    printf("%p %d\n", i, *i);

    return 0;
}

It gives the following output:

004158B8 0
00E1002C 0

It seems the two integer are allocated in two different memory locations.

Is the gcnew Int32() allocated in managed heap? or directly on the stack?

Answer 1

In managed C++ new allocates on unmanaged heap, gcnew - on managed heap. Objects in the managed heap are eligible for garbage collection, while objects in the unmanaged heap are not. Pointers with ^ work like C# references - the runtime tracks them and uses for garbage collection, pointers with * work like normal C++ pointers.

Answer 2

I have got the answer. gcnew will allocate the object on managed heap, even the type is a value type.

Therefore, Int32^ i = gcnew Int32() will allocate the newly created object on managed heap.

The following code can prove this:

#include <stdio.h>
#using <mscorlib.dll>

using namespace System;

int main(void) {
    Object^ o = gcnew Object();
    long j = 0;

    while (GC::GetGeneration(o) == 0) {
        Int32^ i = gcnew Int32();
        j += 4;

        if (j % 100 == 0) {
            printf("%d\n", i);
        }
    }

    printf("Generation 0 collection happens at %ld\n", j);        

    return 0;
}

It runs with output

14849324
14849260
14849196
14849132
14849068
14849004
14848940
14848876
14848812
14848748
14848684
14848620
14848556
14848492
14848428
14848364
Generation 0 collection happens at 146880