diff --git a/examples/ch2-06-qsort/v1-qsort/Makefile b/examples/ch2-06-qsort/01-qsort-v1/Makefile
similarity index 100%
rename from examples/ch2-06-qsort/v1-qsort/Makefile
rename to examples/ch2-06-qsort/01-qsort-v1/Makefile
diff --git a/examples/ch2-06-qsort/v1-qsort/main.c b/examples/ch2-06-qsort/01-qsort-v1/main.c
similarity index 100%
rename from examples/ch2-06-qsort/v1-qsort/main.c
rename to examples/ch2-06-qsort/01-qsort-v1/main.c
diff --git a/examples/ch2-06-qsort/v2-qsort/main.go b/examples/ch2-06-qsort/02-qsort-v2/main.go
similarity index 100%
rename from examples/ch2-06-qsort/v2-qsort/main.go
rename to examples/ch2-06-qsort/02-qsort-v2/main.go
diff --git a/examples/ch2-06-qsort/v2-qsort/qsort.go b/examples/ch2-06-qsort/02-qsort-v2/qsort.go
similarity index 100%
rename from examples/ch2-06-qsort/v2-qsort/qsort.go
rename to examples/ch2-06-qsort/02-qsort-v2/qsort.go
diff --git a/examples/ch2-06-qsort/02-qsort-v2/qsort_test.go b/examples/ch2-06-qsort/02-qsort-v2/qsort_test.go
new file mode 100644
index 0000000..e151f0b
--- /dev/null
+++ b/examples/ch2-06-qsort/02-qsort-v2/qsort_test.go
@@ -0,0 +1,26 @@
+// Copyright © 2018 ChaiShushan <chaishushan{AT}gmail.com>.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+package qsort
+
+import (
+	"sort"
+	"testing"
+	"unsafe"
+)
+
+func TestSort(t *testing.T) {
+	values := []int32{42, 9, 101, 95, 27, 25}
+
+	Sort(unsafe.Pointer(&values[0]),
+		len(values), int(unsafe.Sizeof(values[0])),
+		t_get_go_qsort_compare(),
+	)
+
+	isSorted := sort.SliceIsSorted(values, func(i, j int) bool {
+		return values[i] < values[j]
+	})
+	if !isSorted {
+		t.Fatal("should be sorted")
+	}
+}
diff --git a/examples/ch2-06-qsort/02-qsort-v2/test_helper.go b/examples/ch2-06-qsort/02-qsort-v2/test_helper.go
new file mode 100644
index 0000000..c0d373b
--- /dev/null
+++ b/examples/ch2-06-qsort/02-qsort-v2/test_helper.go
@@ -0,0 +1,21 @@
+// Copyright © 2018 ChaiShushan <chaishushan{AT}gmail.com>.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+package qsort
+
+//extern int t_go_qsort_compare(void* a, void* b);
+import "C"
+
+import (
+	"unsafe"
+)
+
+func t_get_go_qsort_compare() CompareFunc {
+	return CompareFunc(C.t_go_qsort_compare)
+}
+
+//export t_go_qsort_compare
+func t_go_qsort_compare(a, b unsafe.Pointer) C.int {
+	pa, pb := (*C.int)(a), (*C.int)(b)
+	return C.int(*pa - *pb)
+}
diff --git a/examples/ch2-06-qsort/v3-qsort/main.go b/examples/ch2-06-qsort/03-qsort-v3/main.go
similarity index 100%
rename from examples/ch2-06-qsort/v3-qsort/main.go
rename to examples/ch2-06-qsort/03-qsort-v3/main.go
diff --git a/examples/ch2-06-qsort/v3-qsort/sort.go b/examples/ch2-06-qsort/03-qsort-v3/sort.go
similarity index 100%
rename from examples/ch2-06-qsort/v3-qsort/sort.go
rename to examples/ch2-06-qsort/03-qsort-v3/sort.go
diff --git a/examples/ch2-06-qsort/03-qsort-v3/sort_test.go b/examples/ch2-06-qsort/03-qsort-v3/sort_test.go
new file mode 100644
index 0000000..53d5238
--- /dev/null
+++ b/examples/ch2-06-qsort/03-qsort-v3/sort_test.go
@@ -0,0 +1,28 @@
+// Copyright © 2018 ChaiShushan <chaishushan{AT}gmail.com>.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+package qsort
+
+import (
+	"sort"
+	"testing"
+	"unsafe"
+)
+
+func TestSort(t *testing.T) {
+	values := []int32{42, 9, 101, 95, 27, 25}
+
+	Sort(unsafe.Pointer(&values[0]), len(values), int(unsafe.Sizeof(values[0])),
+		func(a, b unsafe.Pointer) int {
+			pa, pb := (*int32)(a), (*int32)(b)
+			return int(*pa - *pb)
+		},
+	)
+
+	isSorted := sort.SliceIsSorted(values, func(i, j int) bool {
+		return values[i] < values[j]
+	})
+	if !isSorted {
+		t.Fatal("should be sorted")
+	}
+}
diff --git a/examples/ch2-06-qsort/v4-qsort/main.go b/examples/ch2-06-qsort/04-qsort-v4/main.go
similarity index 100%
rename from examples/ch2-06-qsort/v4-qsort/main.go
rename to examples/ch2-06-qsort/04-qsort-v4/main.go
diff --git a/examples/ch2-06-qsort/v4-qsort/sort.go b/examples/ch2-06-qsort/04-qsort-v4/sort.go
similarity index 100%
rename from examples/ch2-06-qsort/v4-qsort/sort.go
rename to examples/ch2-06-qsort/04-qsort-v4/sort.go
diff --git a/examples/ch2-06-qsort/04-qsort-v4/sort_test.go b/examples/ch2-06-qsort/04-qsort-v4/sort_test.go
new file mode 100644
index 0000000..472c64a
--- /dev/null
+++ b/examples/ch2-06-qsort/04-qsort-v4/sort_test.go
@@ -0,0 +1,24 @@
+// Copyright © 2018 ChaiShushan <chaishushan{AT}gmail.com>.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+package qsort
+
+import (
+	"sort"
+	"testing"
+)
+
+func TestSlice(t *testing.T) {
+	values := []int32{42, 9, 101, 95, 27, 25}
+
+	Slice(values, func(i, j int) bool {
+		return values[i] < values[j]
+	})
+
+	isSorted := sort.SliceIsSorted(values, func(i, j int) bool {
+		return values[i] < values[j]
+	})
+	if !isSorted {
+		t.Fatal("should be sorted")
+	}
+}