Program to check if strings are rotation of each other or not

Implementation in C:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int isRotation(char *s1, char *s2)
{
int len = strlen(s1);
if(len == strlen(s2) && len >0)
{
char *temp;
void *ptr;
temp = (char*)malloc(sizeof(char)*(len*2 +1));
temp[0] = '\0';
strcat(temp,s1);
strcat(temp,s1);
ptr = strstr(temp, s2);
free(temp);
if(ptr!= NULL)
return 1;
else
return 0;
}
return 0;
}
void main()
{
char *s1 = "waterbottle";
char *s2 = "erbottlewat";
if( isRotation(s1, s2))
{
printf("Yes, s2 is the rotation of s1.");
}
else
{
printf("No, s2 is not the rotation of s1.");
}
}

Time Complexity: Complexity of this function depends on the implementation of strstr function.