i want to evaluate polynomial using linked list

[saad abbasi]

int polynomial:: evaluate_polynomial()
{
int input=0;
temp = NULL;
newnode = NULL;
//int newcoeff=0, newexpo = 0;
int evaluation_result = 0;
temp = head;
cout << "Enter value of X : " ;
cin >> input;
while (temp != NULL)
{
evaluation_result = evaluation_result + pow((coeff*input), expo);
//evaluation_result = (evaluation_result) + (temp->coeff) * (pow(input, expo));
temp = temp->next;
}
return evaluation_result;
}

[saad abbasi]

in while statement there are two formula that click in my mind but both of them are not working correctly .... please help me to make formula for evaluation ....