// This program demonstrates the strcmp and atoi functions.
#include <iostream>
#include <cstring> // For strcmp
#include <cstdlib> // For atoi
#include <cctype> // For isdigit
using namespace std;

bool isEntirelyDigits(char * );
bool isEntirelyDigitsP(char * );

int main()
{
   // Array used to read numbers in string form.
   const int LENGTH = 20;
   char input[LENGTH];

   int total = 0,   // Running total
	 count = 0;  // Number of numbers read
   double average;  // Average

   // Read numbers and computer total of numbers.
   cout << "This program will average a series of numbers.\n";
   cout << "Enter the first number or Q to quit: ";
   cin.getline(input, LENGTH);
   while((strcmp(input,"Q")!= 0)&&(strcmp(input,"q")!= 0))
   {
       //make sure that input is numeric (not just not a Q or q)
       if (isEntirelyDigitsP(input))
       {
        // Keep a running total.
          total += atoi(input);

        // Keep track of how many numbers are entered.
          count++;

       }
       else
            cout<<"This input is non numeric and is being ignored." <<endl;

	// Are there more?
	cout << "Enter the next number or Q to quit: ";
	cin.getline(input,LENGTH);
   }

   // Compute and print average.
   if (count != 0)
   {
	average = double(total) / count;
	cout << "average: " << average << endl;
    }

   return 0;
}

//isDigit for a c-string
bool isEntirelyDigits(char * toExamine)
{
    bool success = true;
    int i=0;
    //isdigit(input)
    while(toExamine[i]!='\0')
    {
        if (!isdigit(toExamine[i]))
            success=false;
        i++;
    }
    return success;
}

//isDigit for a c-string
bool isEntirelyDigitsP(char * toExamine)
{
    bool success = true;
    int i=0;
    //isdigit(input)
    while(*(toExamine+i)!='\0')
    {
        if (!isdigit(*(toExamine+i)))
            success=false;
        i++;
    }
    return success;
}