lvalue中的l指的是location,表示可以寻址。The "l" in value can be thought of as location.
rvalue中的r指的是read,表示可读。The "r" in value can be thought of as "read" value.
c++和++c的区别:
c++即是返回a的值,然后变量a加1,返回需要产生一个临时变量类似于:
{ int temp = c; c = c + 1; return temp; //返回右值 }
++c则为:
{ c = c + 1; return &c; //返回左值 }
显然,前增量不需要中间变量,效率更高。