The latest summary of matters related to the understanding and use of pointers in C language

Definition: A pointer is a variable whose value is the address of another variable. The address represents the location in memory. What needs to be remembered is that the array variable itself is a pointer.

Type of address

Addresses have types. Doesn’t it feel strange? Doesn’t a pointer represent an address? Does an address also have a type? Look at an example:

int    *ip;    /* 一个整型的指针 */

double *dp;    /* 一个 double 型的指针 */

float  *fp;    /* 一个浮点型的指针 */

char   *ch;     /* 一个字符型的指针 */

In fact, a pointer is always just a hexadecimal number representing an address. The so-called type refers to the type of the variable pointed by the pointer.

Using pointers

How to define a pointer, you should know from the previous example, then how to print the hexadecimal address and or the data pointed to by the pointer:

//通过&运算符获取了i的地址并保存到intP中去

int *intP; = &i;

printf("intP存储的地址为：%p，存储的地址指向的数据为：%d\n", intP, *intP);

Pointers can perform operations: , --, , -

In addition, pointers can also be compared using relational operators, such as ==, < and >

int intArr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

//先定义一个指针执行数组第一个元素

int *intArrP = &intArr[0];

printf("此时intArrP存储的地址为：%p，数据为：%d\n", intArrP, *intArrP);

//自增一下看看结果（每增加一次，它都将指向下一个整数位置）

intArrP++;

printf("自增以后intArrP存储的地址为：%p，数据为：%d\n", intArrP, *intArrP);

Pointers You can also point to pointers

int data = 5201314;

int *p1 = &data;

int **p2 = &p1;

printf("%d\n", data); //都是5201314

printf("%d\n", *p1);

printf("%d\n", **p2);

Structures and pointers

The use of pointers in structures is a little special, mainly because of the particularity of the structure itself, and you want to use a value in the structure , generally divided into two situations: the structure itself and the pointer pointing to the structure. See the following example for details:

struct Node

{

    int val;
    
};

//先建立一个结构体数据

struct Node node;

node.val = 1;

struct Node *nodeP; //创建一个指向刚刚的结构体的指针

nodeP = &node;

printf("%d\n", nodeP->val);//指向结构体的指针用->

printf("%d\n", node.val);//结构体自身用.

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