Go Regexp: Does the Dot Character Match Newline by Default?

Go Regexp: Does Any Character Match Newline?

Despite the documentation's statement that the any character (.) in Go's re2 syntax matches any character, including newline (s=true), certain cases indicate otherwise. For example, the following program demonstrates that the any character does not match newline:

<code class="go">import "regexp"

func main() {
    str := "hello\nworld"
    match, _ := regexp.MatchString(".*", str)
    println(match) // false
}</code>

Solution: Dot All Flag

To address this issue, Go's regexp package provides the "dot all" flag (?s). When added to a regular expression, this flag allows the dot character (.) to match newlines.

<code class="go">func main() {
    str := "hello\nworld"
    match, _ := regexp.MatchString("(?s).*", str)
    println(match) // true
}</code>

With the (?s) flag, the any character (.) now matches newline characters. This aligns with the behavior of most other regex engines, which typically do not match newlines by default.

The above is the detailed content of Go Regexp: Does the Dot Character Match Newline by Default?. For more information, please follow other related articles on the PHP Chinese website!