Expressions

Objects and lvalues

An object is a manipulatable region of storage. An lvalue is an expression referring to an object. An obvious example of an lvalue expression is an identifier. There are operators that yield lvalues: for example, if E is an expression of pointer type, then E is an lvalue expression referring to the object to which E points.

An lvalue is modifiable if it meets all criteria below:

• it does not have array type

• it does not have an incomplete type

• it does not have a const-qualified type

The name ``lvalue'' comes from the assignment expression E1 = E2 in which the left operand E1 must be an lvalue expression.

Primary expressions

• Identifiers, constants, string literals, and parenthesized expressions are primary expressions.

• An identifier is a primary expression, provided it has been declared as designating an object (which makes it an lvalue) or a function (which makes it a function designator).

• A constant is a primary expression; its type depends on its form and value.

• A string literal is a primary expression; it is an lvalue.
  

• A parenthesized expression is a primary expression. Its type and value are identical to those of the un-parenthesized version. It is an lvalue, a function designator, or a void expression, according to the type of the un-parenthesized expression.