# alphanumericBoundary

Match boundary between alphanumeric and non-alphanumeric characters

Since R2020b

## Syntax

``pat = alphanumericBoundary``
``pat = alphanumericBoundary(type)``

## Description

example

````pat = alphanumericBoundary` creates a pattern that matches the start or end of a run of letters and numbers. `alphanumericBoundary` can be negated using the `~` operator. When negated, `~alphanumericBoundary` matches the boundary between any two characters except at the start or end of a run of alphanumerics.```

example

````pat = alphanumericBoundary(type)` specifies whether to match at the start or end of a run of letters and numbers. `type` can be `'start'`, `'end'`, or `'either'` (default).```

## Examples

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Use `alphanumericBoundary` to divide text along boundaries between letters and digits and non-alphanumeric characters.

```txt = "123abc .?! def456"; pat = alphanumericBoundary;```

Use `replace` to insert "|" characters at the matched boundaries. This operation shows where these boundaries are in the text that contains a variety of character types.

`replace(txt,pat,"|")`
```ans = "|123abc| .?! |def456|" ```

Use the `"start"` and `"end"` options for `alphanumericBoundary` to match the boundary between letters and digits and non-alphanumeric characters.

Create a string that contains several different character types. Create a pattern that matches any characters between a `"start"` boundary of letters and digits and an `"end"` boundary.

```txt = "123 abc .?! def 456"; pat = alphanumericBoundary("start") + wildcardPattern(1,inf) + alphanumericBoundary("end");```

Extract the pattern.

`boundaries = extract(txt,pat)`
```boundaries = 4x1 string "123" "abc" "def" "456" ```

Use the `~` operator to negate `alphanumericBoundary`. This pattern matches the boundary between two characters when both are alphanumeric characters or neither character is alphanumeric.

Create a string that contains several different character types. Create a pattern that matches a negated `alphanumericBoundary`.

```txt = "123 abc .?!"; pat = ~alphanumericBoundary;```

Use `replace` to insert `"|"` characters to show where ~`alphanumericBoundary `matches.

`boundaries = replace(txt,pat,"|")`
```boundaries = "1|2|3 a|b|c |.|?|!|" ```

## Input Arguments

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Boundary type, specified as `'start'`, `'end'`, or `'either'`.

Data Types: `char` | `string`

## Output Arguments

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Pattern expression, returned as a `pattern` object.

## Version History

Introduced in R2020b