Today, I went to Programmersheaven to read an article about Pointers, Lvalues, and Rvalues. I feel that I have a feeling. I used to understand the pointer to the pointer. At least I have reached our C language teacher. But after reading this article, not only let me deepen the understanding of the pointer, but also more deeply understand the variables. It is just aware of the value that you want to store in him before. He is just a name, about how he is assigned, how to find the value I want is always a fog. Today, I saw that there was a sudden feeling. It turned out that he was such a form. It didn't think about it. Now look at the procedure below: main () {int * iptr; * iptr = 421; Printf ("* iptr =% d / n", * iptr);} Over you have any feelings, you can see What is wrong? Yes, the pointer variable IPTR has not been assigned. He may change very much in the big program. But how is the pointer variable initialized? Variables, any variables, including pointers and other types of two properties: Lvalue and Rvalue (left value and right). But what is the meaning of these two attributes? Take a look at this assigned code snippet: int L = 2; int R = 3; l = r; The pointing address obtains the value of R, then obtains the right value of the L, the left value of the left value to the right value pointed to the right, which is completed once. In the two properties of the variable, the right value stores the address that points to the variable-specific value, and the left value stores that particular value. Through the above analysis, we can get a few conclusions: 1: If you do not assign a value to a variable, then his left value is undefined. 2: The impact of using an undefined variable is not defined, sometimes harmful, sometimes it is fun. 3: A variable is an array (Address, Value). 4: Give a variable to assign a value of the compiler. Give a variable to assign a left value of the programmer. -------------------------------------- - in fact, a variable is an array, his The structure is Storage, Scope, Type, Address, Value.
