C pointer parsing ------ operator & amp; and *

C pointer parsing ------ operators & amp; and *
This article is my learning notes, welcome to reprint, but please note the Source: http://blog.csdn.net/jesson20121020

& Is an address operator. * is a pointer or indirect operator. & The operation result of a is a pointer. the pointer type is a type plus *. The pointer type is a type, the pointer value, that is, the memory zone pointed to by the pointer, is the address of. * P has more computation results. In short, * p is what p points to. It has these characteristics: its type is the type pointed to by p, the address it occupies is the address pointed to by p.

See the following example:

Int a = 5;

Int B;

Int * p;

Int ** q;

P = & a; // The result of & a is a pointer of the int type *, int type, and a type.

* P = 10; // * p result. Here its type is int, and the address it occupies is the address pointed to by p, that is, the address of. Obviously, * p is variable a. The essence of this Code is to assign a value to.

Q = & p; // The result of & p is a pointer. The type is p type plus *. Here it is int **. The Pointer Points to the p type. Here it is int *. The Pointer Points to the p address.

* Q = & B; // * q is a pointer, and the result of & B is a pointer. The types of the two pointers are the same as those of the pointer, so this code is to assign a value to * q.

** Q = 34; // * the q result is what q points to. Here it is a pointer, that is, int *, and another operation is performed on this pointer, the result is an int-type variable. The address it occupies is the address pointed to by * q, that is, the address of B. Therefore, the purpose of this sentence is to assign a value to variable B.

Finally, you can verify the following:

#include 
 
  int main(){int a = 5;    int b;    int *p;    int **q;    printf("a = %d\n",a);    p = &a;            *p = 10;    printf("a = %d\n",a);           q = &p;           *q = &b;             **q = 34;     printf("b = %d\n",b);}
 

Result:

a = 5a = 10b = 34

To understand these two operators, you must grasp the types of the results of the two operations and the types pointed.