实现一个函数，可以左旋字符串中的k个字符

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<time.h>

void dev(char a[],int k) {
	int n = 0;
	char* tmp = (char*)malloc( strlen(a) * sizeof(char));
	for (int i = k; a[i] != '\0'; ++i) {
		tmp[n] = a[i];
		++n;
	}
	for (int j = 0; j < k; ++j, ++n) {
		tmp[n] = a[j];
	}
	for (int j = 0; j < n + 1; ++j) {
		a[j]=tmp[j];
	}
	free(tmp);
}

int main() {
	char a[] = "ABCDEFGH";
	int k;
	printf("左旋几个字符：");
	scanf("%d", &k);
	dev(a, k);
	puts(a);
	system("pause");
}

判断一个字符串是否为另外一个字符串旋转之后的字符串。

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<time.h>

int find(char* a,char* b){
	char* tmp = (char*)calloc(strlen(a) * 2 + 1 ,sizeof(char));
	strcpy(tmp, a);
	strcat(tmp, a);
	if (strstr(tmp, b)) {
		free(tmp);
		return 1;
	}
	else {
		free(tmp);
		return 0;
	}
}

int main() {
	char a[] = "ABCDE";
	char b[] = "BCDEA";
	if (find(a, b)) {
		printf("找到了！\n");
	}
	else {
		printf("没找到！\n");
	}
	system("pause");
}