> ## Documentation Index
> Fetch the complete documentation index at: https://axiom.co/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# isascii

> This page explains how to use the isascii function in APL.

Use the `isascii` function to check whether a string contains only ASCII characters. It returns `true` if every character in the input string belongs to the ASCII character set (for example, character codes 0–127) and `false` otherwise.

The function is useful in scenarios where you want to detect non-ASCII text in logs, validate inputs for encoding compliance, or identify potential anomalies introduced by copy-pasted foreign characters or malformed input in user-submitted data.

## For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

<AccordionGroup>
  <Accordion title="Splunk SPL users">
    Splunk SPL doesn’t have a direct equivalent to `isascii`. To achieve similar functionality, you typically need to use `match()` or custom regular expressions. In contrast, APL provides `isascii` as a simple built-in function, making the check much more concise and performant.

    <CodeGroup>
      ```sql Splunk example theme={null}
      ... | eval is_ascii=if(match(field, "^[\x00-\x7F]+$"), "true", "false")
      ```

      ```kusto APL equivalent theme={null}
      datatable(input:string)
      [
        'hello',
        'こんにちは'
      ]
      | extend is_ascii = isascii(input)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    ANSI SQL doesn’t provide a built-in `isascii` function. You often need to simulate it using regular expressions or character code checks. APL simplifies this with the dedicated `isascii` function.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT input,
             CASE WHEN input ~ '^[\x00-\x7F]+$' THEN true ELSE false END AS is_ascii
      FROM my_table;
      ```

      ```kusto APL equivalent theme={null}
      datatable(input:string)
      [
        'hello',
        'こんにちは'
      ]
      | extend is_ascii = isascii(input)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
isascii(value)
```

### Parameters

| Name  | Type   | Description                                 |
| ----- | ------ | ------------------------------------------- |
| value | string | The input string to check for ASCII content |

### Returns

A `bool` value:

* `true` if all characters in `value` are ASCII characters.
* `false` if any character is outside the ASCII range.

## Use case examples

<Tabs>
  <Tab title="Log analysis">
    Identify non-ASCII characters in request URIs to detect unusual or malformed traffic.

    **Query**

    ```kusto theme={null}
    ['sample-http-logs']
    | extend is_ascii_uri = isascii(uri)
    | summarize count() by is_ascii_uri
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'sample-http-logs'%5D%20%7C%20extend%20is_ascii_uri%20%3D%20isascii\(uri\)%20%7C%20summarize%20count\(\)%20by%20is_ascii_uri%22%7D)

    **Output**

    | is\_ascii\_uri | count\_ |
    | -------------- | ------- |
    | true           | 14250   |
    | false          | 130     |

    This query flags requests with non-ASCII characters in the `uri` field. These entries can indicate abnormal requests or encoding issues in log data.
  </Tab>

  <Tab title="OpenTelemetry traces">
    Detect non-ASCII span IDs, which could indicate instrumentation bugs or encoding anomalies.

    **Query**

    ```kusto theme={null}
    ['otel-demo-traces']
    | extend is_ascii_span_id = isascii(span_id)
    | summarize count() by is_ascii_span_id
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'otel-demo-traces'%5D%20%7C%20extend%20is_ascii_span_id%20%3D%20isascii\(span_id\)%20%7C%20summarize%20count\(\)%20by%20is_ascii_span_id%22%7D)

    **Output**

    | is\_ascii\_span\_id | count\_ |
    | ------------------- | ------- |
    | true                | 28700   |
    | false               | 2       |

    This query validates that span IDs in your telemetry traces contain only ASCII characters. Non-ASCII values may hint at bugs or corrupted trace headers.
  </Tab>

  <Tab title="Security logs">
    Identify requests where user IDs contain non-ASCII characters, which can help detect suspicious or malformed entries.

    **Query**

    ```kusto theme={null}
    ['sample-http-logs']
    | extend is_ascii_id = isascii(id)
    | summarize count() by is_ascii_id
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'sample-http-logs'%5D%20%7C%20extend%20is_ascii_id%20%3D%20isascii\(id\)%20%7C%20summarize%20count\(\)%20by%20is_ascii_id%22%7D)

    **Output**

    | is\_ascii\_id | count |
    | ------------- | ----- |
    | true          | 11900 |
    | false         | 350   |

    This query detects potentially malicious or malformed user IDs by filtering for non-ASCII values in the `id` field.
  </Tab>
</Tabs>