Does the comma operator have to be left-associative?

Question

According to this precedence table, the comma operator is left-associative. That is, a, b, c is parsed as (a, b), c. Is that a necessity? Wouldn't a, (b, c) have the exact same behavior?

Answer 1

Since overloadable operator, exists, no, it's not the same behavior. a, (b, c) could call different overloads than (a, b), c.

Answer 2

The comma operator has left-to-right associativity. Two expressions separated by a comma are evaluated left to right. The left operand is always evaluated, and all side effects are completed before the right operand is evaluated.

Commas can be used as separators in some contexts, such as function argument lists. Do not confuse the use of the comma as a separator with its use as an operator; the two uses are completely different.

http://msdn.microsoft.com/en-us/library/zs06xbxh.aspx