Pointer learning diary (I)

#include
#include
using namespace std;
int main()
{
char* p;
char ch = ‘a’;
p = &ch;
cout << *p << endl;
return 0;
}

You can put char* As a new definition , The value of the variable under this definition is char The address of the type value .

* Operators are indirect access operators , It works with pointers , Used to access the value pointed to by the pointer .

In defining char* p The time should be char* And int,long,char,string The same variable definer .
Defining variables p Is a pointer variable ！ Pointer variables store addresses .* Is the value of the address stored by the access pointer variable

A few pointers that are easy to get wrong

1. *cp+1：* Priority is higher than +, So let's take it first cp A copy of the value pointed to , Add the copy value 1

2. ++cp And cp++; These two are completely different ,++cp Is the addition of variables cp Value （ Variable cp The value of is the address , Then add 1 after , Namely cp The result of the next bit storage space expression of this address is cp I added , And the return value is cp Increased value ）
   and cp++ Return first cp A copy of the value is increased cp Value . Is to return first cp Original value , let cp+1;
   for example ： hypothesis cp The value of is x25（ There is no doubt that it can not ！ Just make an assumption , Storage space takes up one ）.
   that cp++ The return is x25,++cp The return is x26;！ But pay attention to , The two methods ,cp The end result is x26, It's just that the return value is different .

3. Here we go ！*++cp And ++*cp The difference between ：
   *++cp, Indirect access operators （ That is, the asterisk ） Copy of the pointer acting on the increment
   *cp++, suffix ++ The operator takes precedence over the indirect access operator , But the value returned by this expression is cp Original value , It seems that the indirect access operation is performed first , Actually, it involves 3 A step ：++ Operators produce cp A copy of ; then ++ The operator adds cp Value ; Last , stay cp Perform indirect access operations on the replica .

4. ++cp： I want to code this explanation
   #include
   #include
   using namespace std;
   int main()
   {
   char p;
   char* k;
   char ch = ‘a’;
   p = &ch;
   k = p;
   *p = ‘b’;
   cout << ++*p <<” “;
   cout << *k << endl;
   return 0;
   }
   The final result is c c, That is to say, first visit indirectly p operation , Will be p The value of the pointed position increases 1, At this time ！ch The value of has really changed