Embellish random number example, add benchmarks.

rand_between/rand_between.go

@@ -19,11 +19,22 @@ func randBetween(min, max int64) int64 {
 	return br.Add(big.NewInt(min), br).Int64()
 }
 
+func randBetween2(min, max int64) int64 {
+	rt, _ := rand.Int(rand.Reader, big.NewInt(max-min)) // Ignore errors here
+	return min + rt.Int64()
+}
+
+func randBetween3(min, max int64, fact float64) int64 {
+	rt, _ := rand.Int(rand.Reader, big.NewInt(max-min)) // Ignore errors here
+	return int64(fact * float64(min+rt.Int64()))
+}
+
 func main() {
-	fmt.Println("Start...")
 	fmt.Printf("MIN: %d\n", min)
 	fmt.Printf("MAX: %d\n", max)
-	for i := 1; i <= 1000000; i++ {
+	//
+	fmt.Println("StartT1...")
+	for i := 1; i <= 100; i++ {
 		fmt.Printf("Iteration %d\n", i)
 		r := randBetween(min, max)
 		fmt.Printf("Result: %d\n", r)
@@ -32,6 +43,29 @@ func main() {
 			panic("unexpected results")
 		}
 	}
-
-	fmt.Println("End...")
+	fmt.Println("EndT1...")
+	//
+	fmt.Println("StartT2...")
+	for i := 1; i <= 100; i++ {
+		fmt.Printf("Iteration %d\n", i)
+		r := randBetween2(min, max)
+		fmt.Printf("Result: %d\n", r)
+		if r < min || r > max {
+			fmt.Printf("Error, unexpected results: %v, %v, %v\n", min, max, r)
+			panic("unexpected results")
+		}
+	}
+	fmt.Println("EndT2...")
+	//
+	fmt.Println("StartT3...")
+	for i := 1; i <= 100; i++ {
+		fmt.Printf("Iteration %d\n", i)
+		r := randBetween3(min, max, 1.0)
+		fmt.Printf("Result: %d\n", r)
+		if r < min || r > max {
+			fmt.Printf("Error, unexpected results: %v, %v, %v\n", min, max, r)
+			panic("unexpected results")
+		}
+	}
+	fmt.Println("EndT3...")
 }

rand_between/rb_test.go

@@ -0,0 +1,21 @@
+package main
+
+import "testing"
+
+func BenchmarkBetween(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		_ = randBetween(min, max)
+	}
+}
+
+func BenchmarkBetween2(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		_ = randBetween2(min, max)
+	}
+}
+
+func BenchmarkBetween3(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		_ = randBetween3(min, max, 1.0)
+	}
+}