Replace range with direct array access

Author: Alex Kahn

main.go

@@ -79,7 +79,7 @@ func scanRange(id int, start int64, end int64, count *atomic.Int64, wg *sync.Wai
 
 		for i := range bytes {
 			hex.Encode(encoded, bytes[i:i+1])
-			if containsLetter(encoded) {
+			if isLetter(encoded[0]) || isLetter(encoded[1]) {
 				// Found an alphabetical character, move on
 				letterDetected = true
 				break
@@ -101,12 +101,6 @@ func scanRange(id int, start int64, end int64, count *atomic.Int64, wg *sync.Wai
 	}
 }
 
-func containsLetter(id []byte) bool {
-	for _, ch := range id {
-		if ch >= 97 && ch <= 122 {
-			return true
-		}
-	}
-
-	return false
+func isLetter(ch byte) bool {
+	return ch >= 97 && ch <= 122
 }

main_test.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+)
+
+func BenchmarkScanRange(b *testing.B) {
+	wg := sync.WaitGroup{}
+	count := atomic.Int64{}
+
+	for n := 0; n < b.N; n++ {
+		wg.Add(1)
+		scanRange(1, int64(n), int64(n+1), &count, &wg)
+	}
+}

range.go

@@ -0,0 +1 @@
+package main