本文是关于指针和数组的试题分享 首先介绍一个库函数和一个操作符: 1.strlen: 求字符串长度,不包括\0 ![在这里插入图片描述](https://img-blog.csdnimg.cn/01358055442b4a7a800dce5a97e43835.png) 2.sizeof: 操作符,单位是字节 求变量所占空间的大小。求类型创建的变量所占空间的大小。 sizeof求字节数: char:1 short:2 int:4 float:4 在32位平台下(x86)指针变量大小是4个字节,64位下是8个字节
一、一维数组
数组名的意义:
- sizeof(数组名),这里的数组名表示整个数组,计算的是整个数组的大小。
- &数组名,这里的数组名表示整个数组,取出的是整个数组的地址。
- 除此之外所有的数组名都表示首元素的地址。
int main()
{
int a[] = { 1,2,3,4 };
printf("%d\n", sizeof(a));
printf("%d\n", sizeof(a + 0));
printf("%d\n", sizeof(*a));
printf("%d\n", sizeof(a + 1));
printf("%d\n", sizeof(a[1]));
printf("%d\n", sizeof(&a));
printf("%d\n", sizeof(*&a));
printf("%d\n", sizeof(&a + 1));
printf("%d\n", sizeof(&a[0]));
printf("%d\n", sizeof(&a[0] + 1));
}
解析: ![![在这里插入图片描述](https://img-blog.csdnimg.cn/74bed67a35584b1bad3bd9a93ab7eee1.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16二、字符数组](https://img-blog.csdnimg.cn/7bfa30986cda40f18a9c4f1186bd237f.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
二、字符数组
1.char arr[] = {‘a’,‘b’,‘c’,‘d’,‘e’,‘f’};
char arr[] = {'a','b','c','d','e','f'};
printf("%d\n", sizeof(arr));
printf("%d\n", sizeof(arr+0));
printf("%d\n", sizeof(*arr));
printf("%d\n", sizeof(arr[1]));
printf("%d\n", sizeof(&arr));
printf("%d\n", sizeof(&arr+1));
printf("%d\n", sizeof(&arr[0]+1));
printf("%d\n", strlen(arr));
printf("%d\n", strlen(arr+0));
printf("%d\n", strlen(*arr));
printf("%d\n", strlen(arr[1]));
printf("%d\n", strlen(&arr));
printf("%d\n", strlen(&arr+1));
printf("%d\n", strlen(&arr[0]+1));
解析: ![在这里插入图片描述](https://img-blog.csdnimg.cn/2278062c0e2741bebf76716f17be57d5.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
2.char arr[] = “abcdef”;
char arr[] = "abcdef";
printf("%d\n", sizeof(arr));
printf("%d\n", sizeof(arr+0));
printf("%d\n", sizeof(*arr));
printf("%d\n", sizeof(arr[1]));
printf("%d\n", sizeof(&arr));
printf("%d\n", sizeof(&arr+1));
printf("%d\n", sizeof(&arr[0]+1));
printf("%d\n", strlen(arr));
printf("%d\n", strlen(arr+0));
printf("%d\n", strlen(*arr));
printf("%d\n", strlen(arr[1]));
printf("%d\n", strlen(&arr));
printf("%d\n", strlen(&arr+1));
printf("%d\n", strlen(&arr[0]+1));
解析: ![在这里插入图片描述](https://img-blog.csdnimg.cn/d2188b0bad2547c4bf16198bf815bc4f.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16) ![在这里插入图片描述](https://img-blog.csdnimg.cn/60d013150cca41b3b1cd4ecc9602772b.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
3.char *p = “abcdef”;
const char *p = "abcdef";
printf("%d\n", sizeof(p));
printf("%d\n", sizeof(p+1));
printf("%d\n", sizeof(*p));
printf("%d\n", sizeof(p[0]));
printf("%d\n", sizeof(&p));
printf("%d\n", sizeof(&p+1));
printf("%d\n", sizeof(&p[0]+1));
printf("%d\n", strlen(p));
printf("%d\n", strlen(p+1));
printf("%d\n", strlen(*p));
printf("%d\n", strlen(p[0]));
printf("%d\n", strlen(&p));
printf("%d\n", strlen(&p+1));
printf("%d\n", strlen(&p[0]+1));
解析: ![在这里插入图片描述](https://img-blog.csdnimg.cn/e20fe86c92c443f0a6fe966de90af918.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16) ![在这里插入图片描述](https://img-blog.csdnimg.cn/d28e816c1b7149b582a5a50da2257f1b.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_18,color_FFFFFF,t_70,g_se,x_16)
4.二维数组
int a[3][4] = {0};
printf("%d\n",sizeof(a));
printf("%d\n",sizeof(a[0][0]));
printf("%d\n",sizeof(a[0]));
printf("%d\n",sizeof(a[0]+1));
printf("%d\n",sizeof(*(a[0]+1)));
printf("%d\n",sizeof(a+1));
printf("%d\n",sizeof(*(a+1)));
printf("%d\n",sizeof(&a[0]+1));
printf("%d\n",sizeof(*(&a[0]+1)));
printf("%d\n",sizeof(*a));
printf("%d\n",sizeof(a[3]));
![在这里插入图片描述](https://img-blog.csdnimg.cn/e6df53a8af0a485db9cc2d3c34d1ff0d.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16) ![在这里插入图片描述](https://img-blog.csdnimg.cn/701c2f3f0dc045289e0232b4145869d3.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
三、综合题型
例1.
struct Test
{
int Num;
char *pcName;
short sDate;
char cha[2];
short sBa[4];
}*p;
int main()
{
printf("%p\n", p + 0x1);
printf("%p\n", (unsigned long)p + 0x1);
printf("%p\n", (unsigned int*)p + 0x1);
return 0;
}
1.00100014 2.00100001 3.00100004
例2.
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;
}
ptr[-1] --> *(ptr+(-1)) --> *(ptr-1) ![在这里插入图片描述](https://img-blog.csdnimg.cn/be30d5a5243c445197243ac4493ed03a.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
例3.
#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;
}
该题易错点为数组中是逗号表达式,只有3个数据。
例4.
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;
}
两个指针相减结果是两地址之间的元素个数 ![在这里插入图片描述](https://img-blog.csdnimg.cn/597d94aea6ab42daa8c39e2593b1119a.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
例5.
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;
}
![在这里插入图片描述](https://img-blog.csdnimg.cn/90063491779a48eb8c5b525a50fcaf94.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
例6.
![#include <stdio.h>
int main()
{
char *a[] = {"work","at","alibaba"};
char**pa = a;
pa++;
printf("%s\n", *pa);
return 0; }
![在这里插入图片描述](https://img-blog.csdnimg.cn/6f12d1563b054d57bea195a34dde1d01.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_14,color_FFFFFF,t_70,g_se,x_16)
例7.
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;
}
![在这里插入图片描述](https://img-blog.csdnimg.cn/5967ad6d79414d6d8b26c56dfbcd04f2.png?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAeW16MTIzXw==,size_20,color_FFFFFF,t_70,g_se,x_16)
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