What is the difference between *p and p in C language

Difference: 1. The meanings are different. "*p" represents the content stored in the memory address pointed by this pointer. "p" represents the name of a pointer variable, which refers to the memory address pointed by this pointer variable. . 2. The output formats are different. "*p" usually outputs a variable or constant of the same type as the pointer. "p" outputs a hexadecimal number and the address of a pointer. 3. The functions are different. "*p" tells the program to go to that address to retrieve data, and "p" is used to store the address.

The operating environment of this tutorial: windows7 system, c99 version, Dell G3 computer.

Understand *p, p

In C language, *p and p are commonly used A pointer represents a pointer variable.

If you want to use pointers, you need to first understand addresses and data: you can imagine that there are many boxes, each box has a corresponding number, that number is called "address", and the stuff in the box is called "data" .

p is a pointer variable, used to store the address. You can think of it as the number of the box mentioned above. "*" is the dereference operator. You can think of it as opening the box. p means opening p. No. box and take out the data inside.

To put it simply, remember, p stores the address, and p tells the program to go to that address to retrieve data.

In C language, the * sign has three uses, namely:

• The multiplication sign is used for multiplication operations, such as 5*6.

• Declare a pointer, used when defining pointer variables, such as int *p;.

• Indirect operator, obtains the value in the memory pointed to by the pointer, such as printf("%d",*p);.

The difference between *p and p in C language

1. The meanings are different.

*p represents the content stored in the memory address pointed by this pointer.

p represents the name of a pointer variable, which refers to the memory address pointed to by the pointer variable.

2. The output format is different

*p is generally a variable or constant that is consistent with the pointer type.

pThe output is a hexadecimal number and the address of a pointer.

3. Different functions

#*pLet the program go to that address to retrieve the data.

p stores the address.

Example:

#include <stdio.h>

int main(void){ 

int x=3;

int *p,*q;

p=&x,q=&x;

printf("%d\n",*p++);

printf("%d\n",(*q)++);

printf("%d\n",x);

}

The output result is: 3, 3, 4;

Explanation:

Expanded knowledge: *p and **p Difference

int *p: Level one pointer, indicating that the address pointed to by p stores an int type value

int * *p: Second-level pointer, indicating that the address pointed to by p stores a pointer to type int (that is, the address pointed to by p stores a first-level pointer to int)

For example:

int i=10; //定义了一个整型变量
int *p=&i; //定义了一个指针指向这个变量
int **p1=&p; //定义了一个二级指针指向p指针

Then the way to extract the value of 10 is:

printf("i=[%d]\n",*p);
printf("i=[%d]\n",**p1);

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