parenthesis and brace expression

parenthesis expression，as follows:

(exp1[, exp2[,...]])

it will return the last expression value.

expression may be assignment expression , judgment expression or both.

eg:

1.assignment expression:

c = (a=1,b =2)

the result is that c's value is 2.

2.judgment expression:

c = (a =1 , a==1)

the result is that c's value is 1.

3. both

c = (a = 1, (a != 1) && (a =2))

the result is that c's value is 0.

Note: after the last expression, it can‘t add comma.

brace expression， as follows:

{[exp1[;[exp2;[...]]]]}

if only having a expression without semicolon, it return the  value of expression.

c = { a = 12 };

the result is that c's value is 12.

if at least having two expression, and after every expression, you must add a semicolon. But it will return none.

{a=12;b =13;}