C语言代码（指针）20240306
#define _CRT_SECURE_NO_WARNINGS
#define NDEBUG
#include <stdio.h>
#include <string.h>
#include <assert.h>void Func(int arr[],int len)
{int i = 0;int j = len - 1;while (i < j){while (i < j && arr[i] % 2 != 0){证明是奇数i++;}i下标就是偶数了 while (i < j && arr[j] % 2 == 0){证明是偶数j--;}j下标就是奇数了 int tmp = arr[i];arr[i] = arr[j];arr[j] = tmp;}
}
void Show(int arr[], int len)
{for (int i = 0; i < len; i++){printf("%d ", arr[i]);}printf("\n");
}
int main()
{int arr[] = { 1,2,3,4,5,6,7,8,9 };int len = sizeof(arr) / sizeof(arr[0]);Func(arr, len);Show(arr, len);return 0;
}#if 0
int MyStrlen(char* str)
{assert(str != NULL);if (str == NULL){printf("%s\n","NULL");return;}int count = 0;char* p = str;while (*p != '\0'){count++;p++;}return count;
}
int main()
{char* str = "abcdef";int len = MyStrlen(str);printf("%d\n", len);return 0;
}int main()
{int arr[10] = { 1,2,3,4,5,6,7,8,9,10};int* p = arr;for (int i = 0; i < 9; i++){printf("%d ", *(p + i));}return 0;
}int main()
{int* p = NULL;int arr[10] = { 0 };p = arr;int (*p2)[10] = &arr;//整个数组的地址 -》 指针接收这个地址-》存 整个数组 地址的指针 - > 指向数组的指针 return 0;
}void Func1(char src[],int k)
{int len = strlen(src);求得真实的移动次数int time = k % len;for (int i = 0; i < time; i++){每次移动一个char tmp = src[0];int j = 0;for (; j < len-1; j++){移动数据src[j] = src[j + 1];}src[j] = tmp;B C D A}
}
void Func2(char src[], int k)
{会使用到 库函数strcpy() 字符串拷贝strncat()int len = strlen(src);求得真实的移动次数int time = k % len;char tmp[256] = { 0 };从src + time的位置 开始拷贝字符串到tmp里面 strcpy(tmp, src + time);把src开始的元素 拷贝到tmp这个字符串的后面，拷贝time个strncat(tmp,src,time);strcpy(src, tmp);
}
void Reverse(char str[], int i, int j)
{while (i < j){char tmp = str[i];str[i] = str[j];str[j] = tmp;i++;j--;}
}
void Func(char src[], int k)
{int len = strlen(src);int time = k % len;Reverse(src, 0, time - 1);Reverse(src, time, len - 1); Reverse(src, 0, len - 1);
}
int main()
{char str[] = "abcd";Func(str, 3);printf("%s\n", str);/**/char str[] = "abcd";Func(str, 4);char str2[100] = { 0 };strcpy(str2,str);//把str第一个字符开始的数据 拷贝到str2中char str[] = "abcd";char str2[10] = "pool";strcat(str2,str);//在str2的后边 拼接 strstrncat(str2,str,2);//在str2的后边 拼接 str当中的n个字符printf("%s\n", str2);
}void Reverse(char str[])
{int len = strlen(str);char* left = str;char* right = str + len - 1;while (left < right){char tmp = *left;*left = *right;*right = tmp;left++;right--;}
}int main()
{char str[10000] = {0};scanf("%s",str);gets(str);char str[] = "abcdef";char *str = "abcdef";Reverse(str);printf("%s\n", str);return 0;
}int main()
{unsigned long pulArray[] = { 6,7,8,9,10 };unsigned long* pulPtr;pulPtr = pulArray;*(pulPtr + 3) += 3;*(pulPtr + 3) = *(pulPtr + 3)+ 3;printf("%d,%d\n", *pulPtr, *(pulPtr + 3));char ch = 'a';const char* p = &ch;char ch2 = 'b';p = &ch2;*p = 'p';}
int main6()
{int arr[] = { 1,2,3,4,5 };short* p = (short*)arr;int i = 0;for (i = 0; i < 4; i++){*(p + i) = 0;}for (i = 0; i < 5; i++){printf("%d ", arr[i]);}return 0;
}
int Func(int arr[],int len)
{int ret = 0;for (int i = 0; i < len; i++){ret ^= arr[i];}return ret;
}
int main5()
{int arr[] = { 1,2,3,4,5,4,3,2,1 };int ret = Func(arr,sizeof(arr)/sizeof(arr[0]));printf("%d\n", ret);return 0;
}
int i;
int main4()
{i--;if (i > sizeof(i)){printf(">\n");}else{printf("<\n");}return 0;
}
int main3()
{int n = 2;int m = 5;int ret = n ^ m;int count = 0;求ret中二进制1的个数while (ret != 0){ret = ret & (ret - 1);count++;}printf("%d\n", count);return 0;
}
int main2()
{int n = 7;for (int i = 30; i >= 0; i -= 2){printf("%d ", ((n >> i) | 0));}printf("\n");for (int i = 31; i >= 1; i -= 2){printf("%d ", ((n >> i) | 0));}return 0;
}
int main1()
{int n = 7;for (int i = 30; i >= 0; i -= 2) {printf("%d ",((n >> i) & 1));}printf("\n");for (int i = 31; i >= 1; i -= 2){printf("%d ", ((n >> i) & 1));}return 0;
}
#endif
