---
title: "subscript(_:)"
framework: swift
role: symbol
role_heading: Instance Subscript
path: "swift/unsafemutablepointer/subscript(_:)"
---

# subscript(_:)

Reads or updates the pointee at the specified offset from this pointer.

## Declaration

```swift
subscript(i: Int) -> Pointee { get nonmutating set }
```

## Parameters

- `i`: The offset from this pointer at which to access an instance, measured in strides of the pointer’s Pointee type.

## Overview

Overview For a pointer p, the memory at p + i must be initialized when reading the value by using the subscript. When the subscript is used as the left side of an assignment, the memory at p + i is updated. The memory must be initialized or the pointer’s Pointee type must be a trivial type. Uninitialized memory cannot be initialized to a nontrivial type using this subscript. Instead, use an initializing method, such as initialize(to:).