Исходники и презентации

lessons/slices_and_arrays/access_by_index/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+func main() {
+	const elemSize = unsafe.Sizeof(int32(0)) // 4 bytes
+	array := [...]int32{1, 2, 3}
+	pointer := unsafe.Pointer(&array)
+
+	first := *(*int32)(unsafe.Add(pointer, 0*elemSize))  // => data2[0]
+	second := *(*int32)(unsafe.Add(pointer, 1*elemSize)) // => data2[1]
+	third := *(*int32)(unsafe.Add(pointer, 2*elemSize))  // => data2[2]
+
+	dangerous1 := *(*int32)(unsafe.Add(pointer, -1)) // => data2[-1]
+	dangerous2 := *(*int32)(unsafe.Add(pointer, 3))  // => data2[3]
+
+	fmt.Println("correct:", first, second, third)
+	fmt.Println("dangeroues:", dangerous1, dangerous2)
+}