Lvalues and rvalues, cv, cv-qualifed, cv-unqualified etc.

[maluk]

What are lvalues and rvalues as stated in the C++ standard? Also, what is cv-qualified as stated in the C++ standard?

I just know that lvalues can be found on the left side of an operator and rvalues on the right. Also they say lvalues are objects.

What else does lvalue and rvalue mean? Same goes with cv-qualified, cv-unqualified and cv?

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[ArkM]

C++ Standard:
Every expression is either an lvalue or an rvalue.
OK, it's a property of an expression. Now the Standard defines in which contexts may be placed lvalues, rvalues or both. For example, built-in assignment operators all expect their left hand operands to be lvalues. The lvalue may be converted to rvalue (but not vice versa). Binary + operator yields rvalue, then we can't write (x+1) = 3; you can't apply unary & operator to rvalue - etc.

CV is an abbreviation of const-volatile. It's a [byte]type[/b] property. Type without const or/and volatile qualifiers is cv-unqualified.

Each type which is a cv-unqualified ... has three corresponding cv-qualified versions of its type: a const-qualified version, a volatile-qualified version, and a const-volatile-qualified version. ...
The cv-qualified or cv-unqualified versions of a type are distinct types;

Now the Standard defines in strict and precise manner all contexts where cv-qualification may appear or may affect on these types objects behaviour. For example, built-in unary * operators yields (modifiable) lvalue only if its pointer argument is not const-qualified...

Lvalue comes from C. In C++ we can modify an object via rvalue by member function call. There is modifiable-lvalue in C++ (and nonmodifiable lvalue too). But old simple rule works fine: lvalue is an expression which you can place as a left-hand operand of an assignment operator...