C# Memory Management for Unity Developers (part 1 of 3)

https://www.gamasutra.com/blogs/WendelinReich/20131109/203841/C_Memory_Management_for_Unity_Developers_part_1_of_3.php?print=1

• newobj <constructor>: This creates an uninitialized object of the type specified via the constructor. If the object is a value type (struct etc.), it is created on the stack. If it is a reference typ (class etc.) it lands on the heap. You always know the type from the CIL code, so you can tell easily where the allocation occurs.
• newarr <element type>: This instruction creates a new array on the heap. The type of elements is specified in the a parameter.
• box <value type token>: This very specialized instruction performs boxing, which we already discussed in the first part of this series.

Let's look at a rather contrived method that performs all three types of allocations.

void SomeMethod()
{
    object[] myArray = new object[1];
    myArray[0] = 5;

    Dictionary<int, int> myDict = new Dictionary<int, int>();
    myDict[4] = 6;

    foreach (int key in myDict.Keys)
        Console.WriteLine(key);
}

The amount of CIL code generated from these few lines is huge, so I'll just show the key parts here:

IL_0001: newarr [mscorlib]System.Object
...
IL_000a: box [mscorlib]System.Int32
...
IL_0010: newobj instance void class [mscorlib]System.
    Collections.Generic.Dictionary'2<int32, int32>::.ctor()
...
IL_001f: callvirt instance class [mscorlib]System.
    Collections.Generic.Dictionary`2/KeyCollection<!0, !1>
    class [mscorlib]System.Collections.Generic.Dictionary`2<int32,
    int32>::get_Keys()