Pointer (intake)

pointer

Advanced pointer

• Character pointer
• Array pointer
• Pointer array
• Parameter passing pointers and arrays of mass participation
• Function pointer
• Array of function pointers
• Pointer to an array of function pointers
• Callback
• Pointers and arrays resolve questions

In the initial stage of the pointer which, we know that the concept of pointers

• Pointer is a variable used to store address, address uniquely identifies a memory space
• Size of a pointer is fixed 4/8 bytes (32-bit or 64-bit platform internet)
• There is a pointer type, pointer type determines the pointer integer + step, dereferencing operation authority time
• Pointer calculation (± pointer integer, pointer - the pointer, pointer arithmetic comparison)

Character pointer

#include<stdio.h>
int main()
{
	char a = 'w';
	char* pc = &a;   //这个时候，pc称为字符指针，pc的类型为char*
	char arr[10] = "abc";
	char* pa = arr;   //arr作为数组名，他代表的是数组首元素的地址，pa的类型为char*
	char* p = "abcdef";  //此时p只具有4个字节，但是abcdef不算\0有6个字节，显然放不下
	//那么此时，p中存的就是"abcdef"中首个字母a的地址，地址用指针接收，刚好为4个字节
	//上述常量表达式的结果就是首字符a的地址。
}

topic:

#include<stdio.h>
int main()
{
	char arr1[] = "abcdef";
	char arr2[] = "abcdef";
	if (arr1 == arr2)
		printf("arr1==arr2\n");
	else
		printf("arr1!=arr2\n");
	return 0;
	//打印结果为arr1!=arr2
	//原因:因为arr1和arr2会开辟两块空间的大小，虽然都表示的是首字母a的地址
	//但是两块空间的地址是不一样的，所以两块空间中a的地址自然也就是不一样的了。
}

#include<stdio.h>
int main()
{
	char* p1 = "abcdef";
	char* p2 = "abcdef";
	if (p1 == p2)
		printf("p1==p2");
	else
		printf("p1!=p2");
	return 0;
	//打印结果为p1==p2
	//虽然把字符串abcdef地址存在了p1和p2当中，但是两个字符串是一样的
	//都是abcdef，所以首元素a的地址自然也是一样的了
	//abcdef为常量字符串，所以说他是不能被改变的，其实也只会出现一次abcdef
	//但是p1的地址和p2的地址是绝对不一样的。
}