Is the return statement considered to be an expression statement in C?

Question

I heard that if an expression is followed by a semicolon, then it is considered to be an expression statement.

Source: http://farside.ph.utexas.edu/teaching/329/lectures/node11.html

int x = 7;
x = 8;
x++;
x—-;
x = x << 1;

These are all expression statements.

But is this an expression statement too?

return 5;

And if not, then please throughly explain why.

And I would also appreciate it if you could tell whether the return satetement can be considered an expression statement in other languages as well.

Answer 1

A return statement and an expression statement are two different things.

Section 6.8.3 of the C standard gives the syntax for an expression statement:

expression-statement:

• expression_opt;

While section 6.8.6 gives the syntax of a return statement:

jump-statement:

• goto identifier;
• continue;
• break;
• return expression_opt;

Also, this is not an expression statement (in fact not a statement at all):

int x = 7;

But a declaration.

Answer 2

This is basically answered by Expression Versus Statement. The key question is: Does a return evaluate to a value (e.g. could you do x = return 5;?). Clearly it does not, so it is a statement, not an expression. Expression statements are just expressions used as statements; if it's not an expression, it can't be an expression statement, so return does not form an expression statement.