c25.c

//Check if a string is a rotation of another string
#include <stdio.h>
#include <string.h>
int isRotation(const char *str1, const char *str2) 
{
    int len1 = strlen(str1);//12
    int len2 = strlen(str2);//12

    // Check if lengths are equal
    if (len1 != len2) 
    {
        return 0; // Not rotations
    }

    // Create a new string by concatenating str1 with itself
    char concat[2 * len1 + 1];//size 25
    strcpy(concat, str1);//concat=waterbottle
    strcat(concat, str1);//concat=waterbottlewaterbottle

    // Check if str2 is a substring of the concatenated string
    return strstr(concat, str2) != NULL;//checks if erbottlewat exists inside waterbottlewaterbottle 
}                                       //if exists then it returns 1 (true)
int main() 
{
    const char *str1 = "waterbottle";
    const char *str2 = "erbottlewat";

    if (isRotation(str1, str2)) 
    {
        printf("\"%s\" is a rotation of \"%s\".\n", str2, str1);
    } 
    else 
    {
        printf("\"%s\" is not a rotation of \"%s\".\n", str2, str1);
    }
    return 0;
}