> ## 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.

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://axiom.co/docs/feedback

```json
{
  "path": "/apl/scalar-functions/conversion-functions/tostring",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

# tostring

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

Use the `tostring` function to convert various data types to a string representation. This is helpful when you need to normalize values from different sources into string format for string operations, concatenation, or display purposes.

You typically use `tostring` when working with numeric values, booleans, or other types that need to be converted to strings for string manipulation, formatting, or when combining values in string operations.

## 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">
    In Splunk, you use `tostring` or `tostring()` function to convert values to strings. In APL, `tostring` provides similar functionality for converting various types to string format.

    <CodeGroup>
      ```sql Splunk example theme={null}
      ... | eval status_str = tostring(status_code)
      ```

      ```kusto APL equivalent theme={null}
      ... | extend status_str = tostring(status_code)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    In standard SQL, you use `CAST(... AS VARCHAR)` or `TO_CHAR` functions to convert values to strings. In APL, `tostring` provides a simpler way to convert various types to string values.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT CAST(123 AS VARCHAR) AS status_str FROM logs;
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend status_str = tostring(123)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

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

### Parameters

| Name  | Type    | Description                     |
| ----- | ------- | ------------------------------- |
| value | dynamic | The value to convert to string. |

### Returns

If the expression value is non-null, the result is a string representation of the expression. If the expression value is null, the result is an empty string.

### Conversion behavior

The `tostring` function converts values based on their type:

* **Integer**: Formatted as base-10 string.
* **Float**: Formatted using Go’s `FormatFloat` function with precision `-1`. For more information, see the [Go documentation](https://pkg.go.dev/strconv#FormatFloat).
* **Boolean**: Returns `"true"` or `"false"`. Nil Boolean values return `"false"`.
* **Duration**: Returns duration-formatted strings. For example, `"1m20s"`.
* **Datetime**: Returns RFC3339Nano formatted datetime string.

## Use case example

Convert trace attributes to strings for string-based analysis and reporting.

**Query**

```kusto theme={null}
['otel-demo-traces']
| where isnotempty(['attributes.http.response.status_code'])
| extend status_str = tostring(['attributes.http.response.status_code'])
| extend duration_str = tostring(duration)
| extend trace_summary = strcat('Service: ', ['service.name'], ', Status: ', status_str, ', Duration: ', duration_str)
| project _time, trace_id, ['service.name'], status_str, trace_summary
```

[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'otel-demo-traces'%5D%20%7C%20where%20isnotempty\(%5B'attributes.http.response.status_code'%5D\)%20%7C%20extend%20status_str%20%3D%20tostring\(%5B'attributes.http.response.status_code'%5D\)%20%7C%20extend%20duration_str%20%3D%20tostring\(duration\)%20%7C%20extend%20trace_summary%20%3D%20strcat\('Service%3A%20'%2C%20%5B'service.name'%5D%2C%20'%2C%20Status%3A%20'%2C%20status_str%2C%20'%2C%20Duration%3A%20'%2C%20duration_str\)%20%7C%20project%20_time%2C%20trace_id%2C%20%5B'service.name'%5D%2C%20status_str%2C%20trace_summary%22%7D)

**Output**

| \_time           | trace\_id | service.name | status\_str | trace\_summary                                      |
| ---------------- | --------- | ------------ | ----------- | --------------------------------------------------- |
| Jun 24, 09:28:10 | abc123    | frontend     | 200         | Service: frontend, Status: 200, Duration: 150000000 |

This example converts trace attributes to strings and creates a summary message, enabling formatted trace reporting and analysis.

## List of related functions

* [strcat](/apl/scalar-functions/string-functions/strcat): Concatenates strings. Use `strcat` with `tostring` to combine converted values into formatted strings.
* [strcat-delim](/apl/scalar-functions/string-functions/strcat-delim): Concatenates strings with a delimiter. Use `strcat-delim` with `tostring` to join converted values with separators.
* [toint](/apl/scalar-functions/conversion-functions/toint): Converts input to integer. Use `toint` to convert strings back to integers when needed.