---
title: "+=(_:_:)"
framework: swift
role: symbol
role_heading: Operator
path: "swift/duration/+=(_:_:)"
---

# +=(_:_:)

Adds two values and stores the result in the left-hand-side variable.

## Declaration

```swift
static func += (lhs: inout Duration, rhs: Duration)
```

## Parameters

- `lhs`: The first value to add.
- `rhs`: The second value to add.