---
title: "init(start:count:)"
framework: swift
role: symbol
role_heading: Initializer
path: "swift/unsafemutablerawbufferpointer/init(start:count:)"
---

# init(start:count:)

Creates a buffer over the specified number of contiguous bytes starting at the given pointer.

## Declaration

```swift
init(start: UnsafeMutableRawPointer?, count: Int)
```

## Parameters

- `start`: The address of the memory that starts the buffer. If starts is nil, count must be zero. However, count may be zero even for a non-nil start.
- `count`: The number of bytes to include in the buffer. count must not be negative.