---
name: "function::matched"
section: "3stap"
platform: "linux"
package: "systemtap-doc"
version: "5.1-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/function::matched"
---

# function::matched(3stap)

Return a given matched subexpression.

## NAME

function::matched - Return a given matched subexpression.

## SYNOPSIS

```
    matched:string(n:long)
```

## ARGUMENTS

*n*

index to the subexpression to return. 0 corresponds to the entire regular expression.

## DESCRIPTION

returns the content of the n'th subexpression of the last successful use of the =~ regex matching operator. Returns an empty string if the n'th subexpression was not matched (e.g. due to alternation). Throws an error if the last use of =~ was a failed match, or if fewer than n subexpressions are present in the original regexp.

## SEE ALSO0

[*tapset::regex*(3stap)](/tapset::regex/3stap.md)