diff --git a/regex/example_test.go b/regex/example_test.go
index 60ed033..8499dfc 100644
--- a/regex/example_test.go
+++ b/regex/example_test.go
@@ -78,3 +78,14 @@ func ExampleReg_LiteralPrefix() {
 	// Output: a
 	// false
 }
+
+func ExampleReg_Longest() {
+	regexStr := `x|xx`
+	inputStr := "xx"
+	regexComp := regex.MustCompile(regexStr)
+	fmt.Println(regexComp.FindString(inputStr))
+	regexComp.Longest()
+	fmt.Println(regexComp.FindString(inputStr))
+	// Output: x
+	// xx
+}