指针6

数组指针

本质就是一个指针

多维数组指针指向一维数组

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#include "stdafx.h"

char arr[] = {
0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x07,0x09,					
0x00,0x20,0x10,0x03,0x03,0x0C,0x00,0x00,0x44,0x00,					
0x00,0x33,0x00,0x47,0x0C,0x0E,0x00,0x0D,0x00,0x11,					
0x00,0x00,0x00,0x02,0x64,0x00,0x00,0x00,0xAA,0x00,					
0x00,0x00,0x64,0x00,0x00,0x00,0x00,0x00,0x00,0x00,					
0x00,0x00,0x02,0x00,0x74,0x0F,0x41,0x00,0x00,0x00,					
0x01,0x00,0x00,0x00,0x05,0x00,0x00,0x00,0x0A,0x00,					
0x00,0x02,0x74,0x0F,0x41,0x00,0x06,0x08,0x00,0x00,					
0x00,0x00,0x00,0x64,0x00,0x0F,0x00,0x00,0x0D,0x00,					
0x00,0x00,0x23,0x00,0x00,0x64,0x00,0x00,0x64,0x00					
};

int main(int argc, char* argv[])
{
	char (*pa)[2][3][3];

	pa=(char (*)[2][3][3])arr;

	printf("%x",*(*(*(*(pa+2)+3)+2)+2));
    //pa的宽度为，char类型指针去掉一个星号，1*2*3*3=18，加2就是18*2=36字节
    //*(pa+2)的宽度为，1*3*3=9，加3就是3*9=27
    //*(*(pa+2)+3的宽度为，1*3=3，加2就是6
    //最后加2，最终结果是0x02

	getchar();
	return 0;

}

image-20231113105730882

函数指针

既然是指针类型，恒定长度为4字节，函数指针无法进行加法运算，因为函数的宽度无法确定

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#include "stdafx.h"

int x=10;

int fun(int x,int y)
{
	return x+y;
}

int main(int argc, char* argv[])
{
	
	int (*pfun)(int,int);



	printf("%d",sizeof(pfun));

	getchar();
	return 0;

}

image-20231113105913254

通过数据区存放函数

把原加法函数的硬编码复制出去

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// Test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

int x=10;

unsigned char arr[]=
{
0x55,
0x8B, 0xEC,
0x83, 0xEC, 0x40,
0x53,
0x56,
0x57,
0x8D, 0x7D, 0xC0,
0xB9, 0x10, 0x00, 0x00, 0x00,
0xB8, 0xCC, 0xCC, 0xCC, 0xCC,
0xF3, 0xAB,
0x8B, 0x45, 0x08,
0x03, 0x45, 0x0C,
0x5F,
0x5E,
0x5B,
0x8B, 0xE5,
0x5D,
0xC3
};

int main(int argc, char* argv[])
{
	
	int (*p)(int,int);

	p=(int (*)(int,int))&arr;

	int a=p(5,6);
	
	printf("%d",a);

	getchar();
	return 0;

}