Arrays

Array types and allocation

T[] is the array type. The element count belongs to the allocation expression and may be computed at runtime.

int count = GetCount();

int[] temporary = int[count];
int[] persistent = new int[count];

T[n] allocates temporary array storage in the current stack frame. new T[n] allocates array storage on the heap.

Indexing

Use array[index] to read or write an element. The index must be an integer expression.

persistent[0] = 10;
persistent[1] = persistent[0] + 5;

int first = persistent[0];

Stack array lifetime

A stack array is local to the function that allocates it. It may be indexed and assigned locally, but it cannot be returned, passed to another function, or stored in a field or another escaping value.

int SumPair(int left, int right)
{
    int[] values = int[2];
    values[0] = left;
    values[1] = right;
    return values[0] + values[1];
}

Heap array lifetime

A heap array may be passed, returned or stored. Its owner releases the allocation explicitly with free.

void Fill(int[] values)
{
    values[0] = 42;
}

int[] values = new int[16];
Fill(values);
free(values);

Length and native boundaries

The T[] value does not carry its element count. Code that needs bounds keeps the length separately and passes it explicitly. The same pointer-and-length shape is used at a C ABI boundary.

void Process(int[] values, nuint length);
extern void ProcessNative(int* values, nuint length);