Hexkey

int hexKey(char digit,int power)
{
    int arr[]={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15},i;
    char digitList[]={'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
    for(i=0;i<16;i++)
    {
        if(digitList[i]==digit)
            return arr[i]*pow(16,power);
    }
}