# eval

```
Evaluate an expression, in the current scripting language.
     expr - an expression
returns: the expression value.
If there are problems, the returned value will be "IDC_FAILURE: xxx"
where xxx is the error description
Thread-safe function.

string or long eval(string expr);

// Macro to check for evaluation failures:
#define EVAL_FAILURE(code) (value_is_string(code) && substr(code, 0, 13) == "IDC_FAILURE: ")
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hex-rays.com/9.0/developer-guide/idc/idc-api-reference/alphabetical-list-of-idc-functions/1220.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.