指针进阶试题

int a[] = { 1,2,3,4 };

	printf("%d\n", sizeof(a));//16
	printf("%d\n", sizeof(a + 0));//4(这里a表示首元素地址)
	printf("%d\n", sizeof(*a));//4
	printf("%d\n", sizeof(a + 1));//4
	printf("%d\n", sizeof(a[1]));//4
	printf("%d\n", sizeof(&a));//4(取出的整个数组的地址，但是地址的大小只是4)
	printf("%d\n", sizeof(*&a));//16(这里解引用出来的是全部数组的内容)
	printf("%d\n", sizeof(&a + 1));//4
	printf("%d\n", sizeof(&a[0]));//4
	printf("%d\n", sizeof(&a[0] + 1));//4

//字符数组
	char arr[] = { 'a','b','c','d','e','f' };
	printf("%d\n", sizeof(arr));//6
	printf("%d\n", sizeof(arr + 0));//4
	printf("%d\n", sizeof(*arr));//1
	printf("%d\n", sizeof(arr[1]));//1
	printf("%d\n", sizeof(&arr));//4
	printf("%d\n", sizeof(&arr + 1));//4
	printf("%d\n", sizeof(&arr[0] + 1));//4

	printf("%d\n", strlen(arr));//因为字符数组中没有'\0'，所以是随机值
	printf("%d\n", strlen(arr + 0));//首元素地址，随机值
	printf("%d\n", strlen(*arr));//当我们传递a时，'a'的ASCII值是97，那97就作为地址传参，以97作为地址向后找，那就是非法访问内存
	printf("%d\n", strlen(arr[1]));//非法访问内存
	printf("%d\n", strlen(&arr));//arr是数组的地址，数组的地址和首元素地址的值是一样的
	printf("%d\n", strlen(&arr + 1));//随机值
	printf("%d\n", strlen(&arr[0] + 1));//随机值

char arr[] = "abcdef";
	printf("%d\n", sizeof(arr));//7(别忘记\0)
	printf("%d\n", sizeof(arr + 0));//4
	printf("%d\n", sizeof(*arr));//1
	printf("%d\n", sizeof(arr[1]));//1
	printf("%d\n", sizeof(&arr));//4
	printf("%d\n", sizeof(&arr + 1));//4
	printf("%d\n", sizeof(&arr[0] + 1));//4

	printf("%d\n", strlen(arr));//6
	printf("%d\n", strlen(arr + 0));//6
	printf("%d\n", strlen(*arr));//随机值
	printf("%d\n", strlen(arr[1]));//非法访问
	printf("%d\n", strlen(&arr));//6
	printf("%d\n", strlen(&arr + 1));//随机值
	printf("%d\n", strlen(&arr[0] + 1));//5

char* p = "abcdef";
	printf("%d\n", sizeof(p));//4
	printf("%d\n", sizeof(p + 1));//4
	printf("%d\n", sizeof(*p));//1
	printf("%d\n", sizeof(p[0]));//1
	printf("%d\n", sizeof(&p));//4
	printf("%d\n", sizeof(&p + 1));//4
	printf("%d\n", sizeof(&p[0] + 1));//4

	printf("%d\n", strlen(p));//6
	printf("%d\n", strlen(p + 1));//5
	printf("%d\n", strlen(*p));//非法访问
	printf("%d\n", strlen(p[0]));//非法访问
	printf("%d\n", strlen(&p));//随机值
	printf("%d\n", strlen(&p + 1));//随机值
	printf("%d\n", strlen(&p[0] + 1));//5

//二维数组
	int a[3][4] = { 0 };

	printf("%d\n", sizeof(a));//48
	printf("%d\n", sizeof(a[0][0]));//4
	printf("%d\n", sizeof(a[0]));//16 对于二维数组来说，a[0]就是第一行这个一维数组的数组名
	printf("%d\n", sizeof(a[0] + 1));//4 a[0]作为第一行数组名，此时表示数组首元素地址，即a[0][0].a[0]+1,第一行第二个元素的地址
	printf("%d\n", sizeof(*(a[0] + 1)));//4
	printf("%d\n", sizeof(a + 1));//4 第二行的地址
	printf("%d\n", sizeof(*(a + 1)));//4*4=16
	printf("%d\n", sizeof(&a[0] + 1));//4 第二行的地址
	printf("%d\n", sizeof(*(&a[0] + 1)));//4*4=16
	printf("%d\n", sizeof(*a));//4
	printf("%d\n", sizeof(a[3]));//16

int main()
{
int a[5] = { 1, 2, 3, 4, 5 };
int *ptr = (int *)(&a + 1);
printf( "%d,%d", *(a + 1), *(ptr - 1));
return 0;
}
//程序的结果是什么？

//由于还没学习结构体，这里告知结构体的大小是20个字节
struct Test
{
int Num;
char *pcName;
short sDate;
char cha[2];
short sBa[4];
}*p;
//假设p 的值为0x100000。 如下表表达式的值分别为多少？
//已知，结构体Test类型的变量大小是20个字节
int main()
{
printf("%p\n", p + 0x1);
printf("%p\n", (unsigned long)p + 0x1);
printf("%p\n", (unsigned int*)p + 0x1);
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", ptr1[-1], *ptr2);
return 0;
}

#include <stdio.h>
int main()
{
	int a[3][2] = { (0, 1), (2, 3), (4, 5) };
	int* p;
	p = a[0];
	printf("%d", p[0]);
	return 0;
}

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]);
	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", *(ptr1 - 1), *(ptr2 - 1));
	return 0;
}

#include <stdio.h>
int main()
{
	char* a[] = { "work","at","alibaba" };
	char** pa = a;
	pa++;
	printf("%s\n", *pa);
	return 0;
}

int main()
{
	char* c[] = { "ENTER","NEW","POINT","FIRST" };
	char** cp[] = { c + 3,c + 2,c + 1,c };
	char*** cpp = cp;
	printf("%s\n", **++cpp);
	printf("%s\n", *-- * ++cpp + 3);
	printf("%s\n", *cpp[-2] + 3);
	printf("%s\n", cpp[-1][-1] + 1);
	return 0;
}