左值--k&r (A.5)

An object is a named region of storage;
an lvalue is an expression referring to an object.
An obvious example of an lvalue expression is an identifier with suitable type and storage class.There are operators that yield lvalues, if E is an expression of pointer type,then *E is an lvalue expression referring to the object to which E points.The name "lvalue" comes from the assignments expression E1 = E2 in which the left operand E1 must be an lvalue expression.The discussion of each operator specifies whether it expects lvalue operands
and whether it yields an lvalue
命名的存储区域即为对象；
左值为一个表达式，它引用一个对象。
左值一个比较明显的例子是具有类型和存储区域标识符。
运算符也能产生左值，如E是一个指针类型，那么 *E就是一个左值表达式，它引用E指向的对象。左值（Lvalue)的名字来源于赋值表达式：E1 = E2,其中左边的操作数E1必须是一个左值表达式。对运算符的具体讨论会详细说明该运算符是期望一个左值操作数还是该运算符产生一个左值表达式