int atoi(char* string)
{
    int pos = 0;
    int result = 0;
    int factor = 1;
    char letter;

    if (*string == '-')
    {
        factor = -1;
        string++;
    }

    while (*(string+pos)!='\0') pos++;
    while (pos>0)
    {
        letter = *(string+pos-1);
        if (letter < '0' || letter > '9')
            return 0;
        result += (letter - '0') * factor;
        factor *= 10;
        pos --;
    }
    return result;
}

char* strcat(char* str1, char* str2)
{
    int lenstr1 = strlen(str1);
    int lenstr2 = strlen(str2);
    char* result = (char*)malloc(lenstr1+lenstr2);
    char* pos =  result;

    while(lenstr1>0)
    {
        *pos++ = *str1++;
        lenstr1--;
    }
    while(lenstr2>0)
    {
        *pos++ = *str2++;
        lenstr2--;
    }

    return result;
}

char* basename(char* path)
{
    char* p = path+strlen(path)-1;
    while (p > path)
    {
        if(*p == '/')
            return p+1;
        p--;
    }
    return path;

}

int countones(int number)
{
    int count = 0;
    int pattern = 1;
    while (pattern <= number)
    {
        if ((number & pattern) > 0)
        {
            count++;
        }
        pattern *= 2;
    }
    return count;
}

unsigned int rightrotate(unsigned int number, int count)
{
    unsigned int leftover = 0;
    while(count-- > 0)
    {
        leftover = number << (sizeof(unsigned int)*8-1);
        number = (number >> 1) | leftover;
    }
    return number;
}