Word Boundary (Whole Word Match) in GO
Match the whole word `cat` without matching it inside other words like `concatenate` or `category`.
Try it in the GO tester →Pattern
regexGO
\bcat\b (flags: gi)Go (RE2) code
goGo
package main
import (
"fmt"
"regexp"
)
func main() {
re := regexp.MustCompile(`(?i)\bcat\b`)
input := `The cat sat on the mat.`
for _, match := range re.FindAllString(input, -1) {
fmt.Println(match)
}
}Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.
How the pattern works
\b is a zero-width assertion at a word boundary — the position between a word character (\w) and a non-word character (or string edge). Wrapping `cat` in two \b anchors forces the match to start AND end at word boundaries, so `cat` matches but `concat` and `cats` do not.
Examples
Input
The cat sat on the mat.Matches
cat
Input
I will concatenate the strings.No match
—Input
CAT, Cat, cat — all match.Matches
CATCatcat