I don't understand the sentence "as the last element's index is myArr.length-1." Why -1 ?

Question

int [ ] myArr = {6, 42, 3, 7};
int sum=0;
for(int x=0; x<myArr.length; x++) {
sum += myArr[x];
}
System.out.println(sum);

// 58

The condition of the for loop is x<myArr.length, as the last element's index is myArr.length-1.

I don't understand the sentence "as the last element's index is myArr.length-1."

Why -1 ? O, 1 , 2 , 3

Answer 1

myArr.length will return 4. But last element's index is Arr[3]. Array indices start from 0. So, last element's index will always be array.length - 1.

Answer 2

myArr.length returns the length of the array (4 in this case)
the index of the last element is 3 (because the index start from 0, zero is the first element's index)
so to get the index of the last element you just do:

myArr.length - 1

which gives 3 (4 - 1 = 3)

Answer 3

Array's elements numeration starts with zero. So if the size of your array is 4, then the last element will have index 3.
E.g. int [] myArr = { 6, 42, 3, 7 };
myArr[0] = 6
myArr[1] = 42
myArr[2] = 3
myArr[3] = 7 // last element with index 3
myArr.length = 4 // size of array is 4
Please note, that '=' symbol is not an assignment symbol, I've just used it to stamp return values of commands standing left from it