Can I confirm if the string is matching with the first block at my regex

I've the below code:

package main

import (
	"fmt"
	"regexp"
)

func main() {
	str := "This is a delimited string, so let's go"
	re := regexp.MustCompile(`(?i)(This is a delimited string)|delimited|string`)
	matches := re.FindAllString(str, -1)
	fmt.Println("We found", len(matches), "matches, that are:", matches)
}

And getting the output as:

We found 1 matches, that are: [This is a delimited string]

If I changed the str in the above code to be:

str := "This is not a delimited string, so let's go"

Then I'm getting the output as:

We found 2 matches, that are: [delimited string]

Both are correct, but in the first block str which is having 1 match is matching 100% with the first block at my regex, which is This is a delimited string, while str in the second block showing 2 matches, none of them is matching with my first block at my regex.

Is there a way, so I know if the str is matching with the first block at my regex or no, so that I get complete matchorpartial matchis thelen(matches)` is not zero, but the first block at the regex is not matched!

This regular expression:

(?i)(This is a delimited string)|delimited|string

matches the leftmost longest match of these literal strings:

• This is a delimited string,
• delimited, or
• string

Feeding the text This is a delimited string, so let's go to the regular expression, the 1st alternative matches. It is the only match, because it consumed both delimited and string — the search continues at the point following the match.

Feeding your alternate text, This is not a delimited string, so let's go to the regular expression results in 2 matches, because the 1st alternative does not match, but the 2nd (delimited) and the 3rd (string) do.

If you want to know which alternative matched, simply enclose each alternative in parentheses to make it a capturing group:

(?i)(This is a delimited string)|(delimited)|(string)`

Now we can check the value of each capturing group: if it has a length greater than 1, it's the alternative that matched.

https://goplay.tools/snippet/nTm56_al__2

package main

import (
	"fmt"
	"regexp"
)

func main() {
	str := "This is a delimited string, so let's go and find some delimited strings"

	re := regexp.MustCompile(`(?i)(This is a delimited string)|(delimited)|(string)`)

	matches := re.FindAllStringSubmatch(str, -1)

	fmt.Println("Matches:", len(matches))
	for i, match := range matches {
		j := 1
		for j < len(match) && match[j] == "" {
			j++
		}
		fmt.Println("Match", i, "matched alternative", j, "with", match[j])
	}

}