Need help understanding strange array syntax

Question

I found this bit in a book and I don\'t get what it does:

int index = 1;
...
getArray() [index=2]++;

[index=2]++; looks strange to me,

Answer 1

Of course it will be invalid, you're not doing anything with it.

getArray() [index=2]++;

For demonstration i will switch getArray() with myArray which has { 100, 200, 300, 400 }.
Than it's equals to:

myArray[2]++;

myArray[2] will now output: 301
And index will be: 2

Answer 2

Let's break that code:

getArray() [index=2]++;

is equivalent to:

int[] someArray = getArray();  // Assume that's an int[]
index = 2;
someArray[index]++;

The last line is equivalent to:

someArray[index] = someArray[index] + 1;

If you remove that ++, then the 2nd expression is not a valid statement. It just becomes:

getArray() [index];

You have to assign that to some L-Value.

Answer 3

getArray() must return an array of numbers (let's say ints), so getArray() [index=2]++; dissected:

int index = 2;
int[] array = getArray();
array[index] = array[index] + 1;