The comma acts as a separator in declarations, function calls and initializers. In ordinary expressions it is a normal binary operator (just like / or &&), but

The comma acts as a separator in declarations, function calls and initializers. In ordinary expressions it is a normal binary operator (just like / or &&), but has the lowest precedence and simply evaluates the left-hand side, discarding the result, then (in that order) evaluates the right-hand side, returning its value as the result.