# Class KeyBound (3.7.0-rc)

3.7.0-rc 3.6.0 (latest) 3.5.0 3.4.0 3.3.0 3.2.0 2.48.0-rc 2.47.1 2.46.0 2.45.0 2.44.0 2.43.0 2.42.0 2.41.0 2.40.0 2.39.0 2.38.0 2.37.0 2.36.0 2.35.0 2.34.0 2.33.0 2.32.0 2.31.0 2.30.0 2.29.0 2.28.0 2.27.0 2.26.0 2.25.1 2.24.0 2.23.0 2.22.1 2.21.0 2.20.0 2.19.0 2.18.0 2.17.0 2.16.0 2.15.1 2.14.0 2.13.0 2.12.0 2.11.0 The [`KeyBound`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1KeyBound) class is a regular type that represents an open or closed endpoint for a range of keys.
A range of keys is defined by a starting [`KeyBound`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1KeyBound) and an ending [`KeyBound`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1KeyBound), and it logically includes all intermediate keys, optionally including/excluding the bounds.

[`KeyBound`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1KeyBound)s can be "open", meaning the matching row will be excluded from the results, or "closed" meaning the matching row will be included. [`KeyBound`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1KeyBound) instances should be created with the [`MakeKeyBoundOpen()`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/namespacegoogle_1_1cloud_1_1spanner) or [`MakeKeyBoundClosed()`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/namespacegoogle_1_1cloud_1_1spanner) factory functions.

###### Example

      auto key_set = spanner::KeySet().AddRange(spanner::MakeKeyBoundOpen(0),
                                                spanner::MakeKeyBoundOpen(11));

###### Example

      auto delete_singers_range =
          spanner::DeleteMutationBuilder(
              "Singers", spanner::KeySet().AddRange(spanner::MakeKeyBoundClosed(3),
                                                    spanner::MakeKeyBoundOpen(5)))
              .Build();

## Constructors

### KeyBound(KeyBound const \&)

Copy and move semantics.

| **Parameter** ||
|---|---|
| **Name** | **Description** |
|   | `KeyBound const &` |

### KeyBound(KeyBound \&\&)

Copy and move semantics.

| **Parameter** ||
|---|---|
| **Name** | **Description** |
|   | `KeyBound &&` |

### KeyBound()

Not default constructible.

### KeyBound(Key, Bound)

Constructs an instance with the given `key` and `bound`.

| **Parameters** ||
|---|---|
| **Name** | **Description** |
| `key` | `Key` |
| `bound` | `Bound` |

## Operators

### operator=(KeyBound const \&)

Copy and move semantics.

| **Parameter** ||
|---|---|
| **Name** | **Description** |
|   | `KeyBound const &` |

| **Returns** ||
|---|---|
| **Type** | **Description** |
| `KeyBound &` |   |

### operator=(KeyBound \&\&)

Copy and move semantics.

| **Parameter** ||
|---|---|
| **Name** | **Description** |
|   | `KeyBound &&` |

| **Returns** ||
|---|---|
| **Type** | **Description** |
| `KeyBound &` |   |

## Functions

### key() const \&

Returns the `Key`.

| **Returns** ||
|---|---|
| **Type** | **Description** |
| `Key const &` |   |

### key() \&\&

Returns the `Key` (by move).

| **Returns** ||
|---|---|
| **Type** | **Description** |
| `Key &&` |   |

### bound() const

Returns the `Bound`.

| **Returns** ||
|---|---|
| **Type** | **Description** |
| `Bound` |   |

## Enum

### google::cloud::spanner::KeyBound::Bound

An enum indicating whether the `Key` is included (closed) or excluded (open).