C语言三种方法实现字符串左旋

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<assert.h>
void Left_Spin(char arr[], int len, int k)
{
assert(arr);
assert(len > 0);
int i = 0;
int temp = 0;
temp = arr[0];
int n = 0;
for (n = 0; n < k; n++)
{
for (i = 0; i < len; i++)
{
arr[i] = arr[i + 1];
}
arr[len-1] = temp;
}
}
int main()
{
int num = 0;
char array[] = "abcdef";
int len = strlen(array);
printf("Please  Enter number:");
scanf("%d", &num);
printf("Before:%s\n", array);
Left_Spin(array,len,num);
printf("After:%s\n", array);
system("pause");
return 0;

}

//方法二：把字符串分成两部分，
//一部分为：从字符串的开始-左旋的次数-1位置的字符串。
//另一部分为：左旋的次数-1位置的字符串到结尾的位的位置
#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<assert.h>
void Swap(char *x, char *y)
{
*x ^= *y;
*y ^= *x;
*x ^= *y;
}
void Left_Spin(char arr[], int len, int k)
{
assert(arr);
assert(len > 0);
char *start = arr;
char *middle = arr + (k - 1);
char *end = arr + len - 1;
while (start < middle)
{
Swap(start, middle);
start++;
middle--;
}
start = arr;
middle = arr + (k - 1);
while (middle + 1 < end)
{
Swap(middle + 1, end);
middle++;
end--;
}
end = arr + len - 1;
while (start < end)
{
Swap(start, end);
start++;
end--;
}
}
int main()
{
int num = 0;
char array[] = "abcdef";
int len = strlen(array);
printf("Please enter number:\n");
scanf("%d", &num);
num %= len;
printf("Before:%s\n", array);
Left_Spin(array, len, num);
printf("After:%s", array);
system("pause");
return 0;

}

//方法三：进行开辟双倍字符串空间
#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<assert.h>
void Left_Spin(char arr[], int len, int k)
{
assert(arr);
assert(len > 0);
char *Buff=NULL;
char *start_Buff = Buff;
Buff = (char*)malloc(2 * len+1);
strcpy(Buff, arr);
strcat(Buff, arr);
strncpy(arr, Buff + k,len);
}
int main()
{
int num = 0;
char array[] = "abcdef";
int len = strlen(array);
printf("Please enter number:\n");
scanf("%d", &num);
num %= len;
printf("Before:%s\n", array);
Left_Spin(array, len, num);
printf("After:%s", array);
system("pause");
return 0;

}