Constant pointer and pointer constant

Detailed explanation of the difference between constant pointer and pointer constant

* ( The pointer ) and const ( Constant ) Read who is first ;
* Symbolic pointer ,const Symbolic content ;
No one is allowed to change who is in front

1. Constant pointer

int a = 10;
int b = 20;
const int* p = &a; //const before , Defined as a constant pointer 
p = &b; // correct , The direction of the pointer can be changed 
//*p = 20; // error , The value pointed by the pointer cannot be changed 

characteristic ： Pointer pointing （ Address to ） You can modify , But the value the pointer points to cannot be changed
（ Content cannot be reassigned , The content can be changed by changing the address to point to the post transformation ）

Constant pointers are essentially pointers , Constant modifies it , Indicates that this pointer is a pointer to a constant （ Variable ）. The object that the pointer points to is a constant , Then this object cannot be changed .

2. constant pointer

int a = 10;
int b = 20;
int* const p = &a; //* before , Defined as a pointer constant 
*p = 20; // correct , The value the pointer points to can be changed 
//p = &b; // error , The pointer cannot be changed 

characteristic ： Pointer pointing （ Address to ） Cannot be modified , The value the pointer points to can be modified .
Must be initialized , Address follows life .

The nature of a pointer constant is a constant , And use pointers to decorate it , So the value of this constant should be a pointer

Expand ：
this The essence of a pointer is constant pointer The point of the pointer cannot be changed