[C++] c语言_Day31_08_01

int main()
{
int a[5] = { 1,2,3,4,5 };
int ptr = (int)(&a + 1);
printf("%d %d\n", *(a + 1), (ptr - 1));  // 2 5
return 0;
}

struct Test
{
int num;
char pcName;
short sDate;
char cha[2];
short sBa[4];
}* p;
int main()
{
p = (struct Test)0x100000;
printf("%p\n", p + 0x1);  // 0x100014
printf("%p\n", (unsigned long)p + 0x1); // 0x100001
printf("%p\n", (unsigned int)p + 0x1); // 0x100004
return 0;
}

int main()
{
int a[4] = { 1,2,3,4 };
int* ptr1 = (int)(&a + 1);
int ptr2 = (int*)((int)a + 1);
printf("%x %x\n", ptr1[-1], ptr2); // 4 2000000
return 0;
}

ptr2先将a的首元素地址强制类型转换为整形再加1
后再强制类型转换为整形指针，其效果为指针在原来的基础上增长1步长。
ptr2原指向内存为01 00 00 00，现ptr2指向内存为00 00 00 02

int main()
{
int a[5][5];
int(p)[4];
p = a;
printf("%p, %d\n", &p[4][2] - &a[4][2], &p[4][2] - &a[4][2]); //FFFFFFFC, -4
return 0;
}

int main()
{
int aa[2][5] = { 1,2,3,4,5,6,7,8,9,10 };
int* ptr1 = (int)(&aa + 1);
int ptr2 = (int*)((aa + 1));
printf("%d %d\n", (ptr1 - 1), *(ptr2 - 1));  // 10 5
return 0;
}

int main()
{
char* a[] = { "work", "at", "alibaba" };
char** pa = a;
pa++;
printf("%s\n", pa);  // at
}

char c[] = { "ENTER", "NEW", "POINT", "FIRST" };
char** cp[] = { c + 3, c + 2, c + 1, c };
char*** cpp = cp;

printf("%s\n", **++cpp);  // POINT
printf("%s\n", --++cpp + 3);  // ER
printf("%s\n", *cpp[-2] + 3);   // ST
printf("%s\n", cpp[-1][-1] + 1);// EW