Array#lastIndex property has been added to stdlib

libraries/stdlib/src/kotlin/Arrays.kt

@@ -124,3 +124,30 @@ public inline fun <T> Array<T>.isEmpty() : Boolean = this.size == 0
 
 /** Returns the array if its not null or else returns an empty array */
 public inline fun <T> Array<T>?.orEmpty() : Array<T> = if (this != null) this else array<T>()
+
+public inline val          BooleanArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val             ByteArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val            ShortArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val              IntArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val             LongArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val            FloatArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val           DoubleArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val             CharArray.lastIndex : Int
+    get() = this.size - 1
+
+public inline val <in T: Any?> Array<T>.lastIndex : Int
+    get() = this.size - 1

libraries/stdlib/test/ArraysTest.kt

@@ -39,4 +39,22 @@ class ArraysTest() : TestCase() {
         assertFalse(iter.hasNext, "Invalid length (hasNext)")
     }
 
+    fun testEmptyArrayLastIndex() {
+        val arr1 = IntArray(0)
+        assertEquals(-1, arr1.lastIndex)
+
+        val arr2 = Array<String>(0, {"$it"})
+        assertEquals(-1, arr2.lastIndex)
+    }
+
+    fun testArrayLastIndex() {
+        val arr1 = intArray(0, 1, 2, 3, 4)
+        assertEquals(4, arr1.lastIndex)
+        assertEquals(4, arr1[arr1.lastIndex])
+
+        val arr2 = Array<String>(5, {"$it"})
+        assertEquals(4, arr2.lastIndex)
+        assertEquals("4", arr2[arr2.lastIndex])
+    }
+
 }