Question

Any computer language have ‘expression’ and ‘statement’. in concept, what’s the diff?

Answer 1

Taken from the wikipedia :

In most languages, statements contrast with expressions in that
statements do not return results and are executed solely for their
side effects, while expressions always return a result and often do
not have side effects at all. Among imperative programming languages,
Algol 68 is one of the few in which a statement can return a result.
In languages which mix imperative and functional styles, such as the
Lisp family, the distinction between expressions and statements is not
made: even expressions executed in sequential contexts solely for
their side effects and whose return values are not used are considered
‘expressions’. In purely functional programming, there are no
statements; everything is an expression.