Understanding of C pointer

C Understanding of pointer

The pointer （ An object in a programming language ）: The pointer is the memory address , Pointer variables are variables used to store memory addresses , In the same CPU Under Framework , Different types of pointer variables occupy the same length of storage unit , Depending on the type of data stored in the variable , The amount of storage space used is also different .

int a=3; // Common variable definitions 

Defining variables a When , The computer will give a Open up a memory space , This memory space is a The address of . For example 0xA0. What's in memory is 3 This value .

int *p;// Define a pointer 
p = &a;// Pointer assignment 

When defining pointers , The computer will also give p Open up a memory space , For example, the memory address is 0XB0.p=&a It means that you will a To the pointer , Stored in the memory of the pointer . That is to say Put a memory address in the memory space , Not a number or a constant .

*p;// Indicates to fetch the pointer address （p Address in memory ） Value pointed to （a Value in memory ）.*p=3

p;// ordinary p The pointer ,p Address stored in （ The content is 0XA0）, Unlike other variables that hold values or constants 
&p;// Express p The address of （ Computer assigned address ）, The content is 0XB0
*p;// Indicates the contents of the address pointed to by the pointer , The content is 3