3.21study(指针)

#include <stdio.h>


/*
void test(int arr[])
{
  int sz = sizeof(arr) / sizeof(arr[0]);//
  printf("%d\n",sz);
}

int main()
{
  int arr[10] = { 0 };
  test(arr);//1/2   1-->x86  2-->x64
  return 0;
}
*/

/*
int main()
{
  char ch = 'w';
  char* pc = &ch;

  return 0;
}
*/

/*
int main()
{
  char arr[] = "abcdef";
  char* pc = arr;
  printf("%s\n",arr);
  printf("%s\n",pc);
  return 0;
}
*/

/*
int main()
{
  char* p = "abcdef";//"abcdef"是常量字符串
  printf("%c\n",*p);//只打印了a
  printf("%s\n",p);//abcdef
  return 0;
}
*/

/*
int main()
{
  char arr1[] = "abcdef";
  char arr2[] = "abcdef";
  char* p1 = "abcdef";//常量字符串
  char* p2 = "abcdef";//常量字符串，在内存中不会改变，在内存中存的同样的地址
  
  //if (arr1 == arr2)
  //{
  //  printf("等于\n");
  //}
  //else
  //{
  //  printf("不等于\n");//√
  //  //两个数组开辟的是不同的空间，故不相等

  //}
  
if (p1 == p2)
{
  printf("等于\n");
}
else
{
  printf("不等于\n");


}
return 0;
}
*/

/*
int main()
{
  int arr[10] = { 0 };//整形数组
  char ch[5] = { 0 };//字符数组
  int* parr[4];//存放整形指针的数组-->指针数组
  char* pch[5];//存放字符指针的数组-->指针数组
  return 0;
}
*/

/*
int main()
{
  int a = 10;
  int b = 20;
  int c = 30;
  int d = 40;
  int* arr[4] = { &a,&b,&c,&d };
  int i = 0;
  for (i = 0; i < 4; i++)
  {
    printf("%d\n",*arr[i]);
  }
  return 0;
}
*/

/*
int main()
{
  int arr1[] = { 1,2,3,4,5 };
  int arr2[] = { 2,3,4,5,6 };
  int arr3[] = { 3,4,5,6,7 };

  int* parr[] = { arr1,arr2,arr3 };//指针数组
  int i = 0;
  for (i = 0; i < 3; i++)
  {
    int j = 0;
    for (j = 0; j < 5; j++)
    {
      printf("%d ", *(parr[i] + j));
    }
    printf("\n");
  }
  //1 2 3 4 5
  //2 3 4 5 6
  //3 4 5 6 7
  return 0;
}
*/

/*
int main()
{//数组指针--指针
  int *p = NULL;//整形指针 --指向整形的指针  -- 可以存放整形的地址
  char* pc = NULL;//pc是字符指针 --指向字符的指针 --可以存放字符的地址
  //数组指针 --指向数组的指针 --存放数组的地址
  int arr[10] = { 0 };
  //arr -首元素的地址
  //&arr[0]-首元素的地址
  //&arr -数组的地址

  int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
  int (*p)[10] = &arr;
  //p为数组指针,指向[10]的数组

  return 0;
}
*/

/*
int main()
{
  char*arr[5];
  char* (*pa)[5] = &arr;

  int arr2[10] = { 0 };
  int (*pa2)[10] = &arr2;
  return 0;
}
*/

/*
int main()
{
  int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
  int(*pa)[10] = &arr;
  int* p = arr;
  int i = 0;
  for (i = 0; i < 10; i++)
  {
    printf("%d ",*(p+i));
  }
  //for (i = 0; i < 10; i++)
  //{
  //  printf("%d ", *(*pa + i));
  //  //printf("%d\ ",(*pa)[i]);
  //}

  return 0;
}
*/

/*
void print1(int arr[3][5],int x,int y)
{
  int  i = 0;
  int j = 0;
  for (i = 0; i < x; i++)
  {
    for (j = 0; j < y; j++)
    {
      printf("%d ",arr[i][j]);
    }
    printf("\n");
  }
}

void print2(int (*p)[5], int x, int y)
{
  int i = 0;
  for (i = 0; i < x; i++)
  {
    int j = 0;
    for (j = 0; j < y; j++)
    {
      printf("%d ", p[i][j]);//结果相同
      printf("%d ", *(p[i] + j);
      printf("%d ", *(*(p + i)) + j);
      printf("%d ",(*(p+i))[j]);//p+i找到某行地址，加*解引用，[j]再访问某个元素
    }
    printf("\n");
  }
}

int main()
{//常用形式，数组指针用在二维以上数组方便
  int arr[3][5] = { {1,2,3,4,5},{2,3,4,5,6},{3,4,5,6,7} };
  print1(arr,3,5);//数组名 - 数组名就是首元素地址 - 把二维数组想象成一维数组即把三行看成三个元素
  //首元素为第一行的地址,传入下部print2为一维5元素数组
  print2(arr,3,5);
  return 0;
}
*/

int main()
{
  int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
  int i = 0;
  int* p = arr;
  for (i = 0; i < 10; i++)
  {
    printf("%d ",*(p+i));
    printf("%d ",*(arr+i));
    printf("%d ",arr[i]);//arr[i]==*(arr+i)=*(p+i)==p[i]
    printf("%d ",p[i]);
  }

  return 0;
}