指针初阶题目演示

指针初阶题目演示

1.求下面代码的输出结果:

#include<stdio.h>
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));
}

结果为:

2…求下面代码的输出结果:

#include<stdio.h>
int main()
{
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));
}

结果为:

3…求下面代码的输出结果:

#include<stdio.h>
int main()
{
char arr[] = { 'a','b','c','d','e','f' };
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));
}

结果为:输出全部为未定义行为,因为这个字符数组没有’\0’

4…求下面代码的输出结果:

#include<stdio.h>
int main()
{
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));
}

结果为:

5…求下面代码的输出结果:

#include<stdio.h>
int main()
{
char arr[] = "abcdef";
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));
}

结果为:6,6,未定义行为,未定义行为,6,未定义行为,5

6.求下面代码的输出结果:

#include<stdio.h>
int main()
{
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));
}

结果为:

7.求下面代码的输出结果:

#include<stdio.h>
int main()
{
char*p = "abcdef";
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));
}

结果为:6,5,未定义行为,未定义行为,未定义行为,未定义行为,5

8.求下面代码的输出结果:

#include<stdio.h>
int main()
{
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]));
}

结果为:

9.求下面代码的输出结果:

#include<stdio.h>
int main()
{
char a[3][5] = { '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]));
}

结果为: