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This article will introduce pointer arrays and array pointers to understand the difference between the two. Learn the difference between array name, & array name (take address array name). Master character pointers, function pointers, and other related content.

1. Distinguish between pointer array and array pointer

Let's look at an example first:

//定义如下两个变量
int *p1[10];
int (*p2)[10];

How to distinguish whether p1 and p2 are pointer arrays or array pointers ?
Before that, let's understand the corresponding concepts of the two.

(1) Pointer array: Simply speaking, a pointer array is an array that stores pointers .
(2) Array pointer : A pointer that can point to an array .
Note: The meaning of the two can be distinguished by the last two words .
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Analyze the above example:

int *p1[10];    //指针数组

int (*p2)[10];  //数组指针

Note: The priority of [ ] is higher than that of * , so p1 will be combined with [ ] first to form an array, and the elements stored in the array are pointers.
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2. Distinguish between array name and & array name

Define the following arrays:

int a[10];

a: The name of the array, indicating the address of the first element of the array.
If the address of the array name a is taken, namely: &a , what does &a mean?
Here is an example to illustrate this problem:

#include <stdio.h>
int main()
{
    
    
    int a[10] = {
    
     0 };
    printf("%p\n", a);
    printf("%p\n", &a);
    printf("===================\n");
    printf("%p\n", a + 1);  //a+1
    printf("%p\n", &a + 1); //&a+1
    return 0;
}

The results are analyzed as follows:
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Summary: &a represents the address of the array , not the address of the first element of the array.
&a+1 represents the address of the entire array +1 , skipping the size of the entire array.

3. Character pointer

Common character pointers: char * p;
(1) Use method 1:

#include <stdio.h>
int main()
{
    
    
    char c = 'A';
    char *p = &c;
    printf("%c\n", *p);
    return 0;
}

Result:
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(2) Use method 2:

#include <stdio.h>
int main()
{
    
    
    char* p = "hello";
    printf("%s\n", p);
    return 0;
}

Results Analysis:
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Note the following example:

#include <stdio.h>
int main()
{
    
    
    char s1[] = "hahahaha!";
    char s2[] = "hahahaha!";
    char *s3 = "hahahaha!";
    char *s4 = "hahahaha!";
    if(s1 ==s2)
 	printf("s1 =  s2\n");
    else
 	printf("s1 != s2\n");
    if(s3 ==s4)
 	printf("s3 = s4\n");
    else
 	printf("s3 != s4\n");
    return 0;
}

Result analysis:
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4. Function pointer

Function pointer: A pointer used to store the address of a function.
For example:

#include <stdio.h>
void print()
{
    
    
 	printf("hello\n");
}
int main()
{
    
    
 printf("%p\n", print);
 printf("%p\n", &print);
 return 0;
}

If you want to save the function address in the above example with a pointer, you need to use a function pointer.
Right now:void (*print)();

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Common function pointers are:

int(*fun1)(int,int);
void(*fun2)(int);
char(*fun3)();

Summarize

That's all for this article.

C language pointer array, array pointer analysis (array name, & array name (take address array name), character pointer, function pointer, etc.)

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