Question

I’m not sure if the term’s actually ‘Array Addition’.

I’m trying to understand what does the following line do:

int var[2 + 1] = {2, 1}; 

How is that different from int var[3]?

I’ve been using Java for several years, so I’d appreciate if explained using Java-friendly words.

Edit: Thousands of thanks to everyone who helped me out, Occam’s Razor applies here.

Answer 1

It’s not different. C++ allows expressions (even non-constant expressions) in the subscripts of array declarations (with some limitations; anything other than the initial subscript on a multi-dimensional array must be constant).

int var[];  // illegal int var[] = {2,1};  // automatically sized to 2 int var[3] = {2,1};  // equivalent to {2,1,0}: anything not specified is zero int var[3];  // however, with no initializer, nothing is initialized to zero

Perhaps the code you are reading writes 2 + 1 instead of 3 as a reminder that a trailing 0 is intentional.