# Regex find

> Supported in: Batch, Faster, Streaming

Matches an expression against a regular expression. Regular expression can match any part of the string.

**Expression categories:** Regex, String

## Declared arguments

* **Expression:** The expression to match against the regular expression.<br>*Expression\<String>*
* **Regex:** The regular expression to find.<br>*Expression\<String>*

**Output type:** *Boolean*

## Examples

### Example 1: Base case

**Description:** The pattern must be in the string but does not have to match the full value.

**Argument values:**

* **Expression:** abcdefg
* **Regex:** abc

**Output:** true

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### Example 2: Base case

**Description:** You can find regex patterns.

**Argument values:**

* **Expression:** abcdefg
* **Regex:** abc?d

**Output:** true

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### Example 3: Base case

**Description:** Regex patterns sometimes don't match input strings.

**Argument values:**

* **Expression:** abdefg
* **Regex:** ab?d

**Output:** true

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### Example 4: Null case (ANSI mode on)

**Description:** Null patterns propagate to null.

**Argument values:**

* **Expression:** foo
* **Regex:** *null*

**Output:** *null*

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### Example 5: Null case (ANSI mode on)

**Description:** Null columns propagate to null.

**Argument values:**

* **Expression:** *null*
* **Regex:** ab?d.\*

**Output:** *null*

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### Example 6: Null case (ANSI mode on)

**Argument values:**

* **Expression:** `foo`
* **Regex:** `pattern`

| foo | pattern | **Output** |
| ----- | ----- | ----- |
| foo | ( | false |
| foo | *null* | *null* |
| *null* | foo | *null* |
| *null* | *null* | *null* |

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### Example 7: Null case

**Description:** Can match using back tracking.

**Argument values:**

* **Expression:** hello hello
* **Regex:** (hello) \1

**Output:** true

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### Example 8: Null case

**Description:** Can match using lookahead.

**Argument values:**

* **Expression:** helloworld
* **Regex:** (\w+)(?=world)

**Output:** true

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### Example 9: Null case (ANSI mode off)

**Description:** Null pattern do not match.

**Argument values:**

* **Expression:** foo
* **Regex:** *null*

**Output:** false

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### Example 10: Null case (ANSI mode off)

**Description:** Null columns do not match.

**Argument values:**

* **Expression:** *null*
* **Regex:** ab?d.\*

**Output:** false

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### Example 11: Null case (ANSI mode off)

**Argument values:**

* **Expression:** `foo`
* **Regex:** `pattern`

| foo | pattern | **Output** |
| ----- | ----- | ----- |
| foo | ( | false |
| foo | *null* | false |
| *null* | foo | false |
| *null* | *null* | false |

***