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 str
strncat(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