n00b input validation...

// What is likely a far too complex/cludgy/etc. attempt at basic input validation? :s
#include <cctype>  // for isalpha() - isdigit() - and friends
#include <cstdlib> // for atoi()
#include <cstring> // for strlen()
#include <iomanip> // for setw()
#include <iostream>

using namespace std;

// Input validation function prototypes
bool isWholeNum (char[]);
bool isAlphaStr (char[]);

int main()
{
    char a;
    char firstName[16], lastName[16], age[4];

    do
    {
        cout << "\nEnter your first name: ";
        cin >> setw(16) >> firstName;
        cin.ignore(1000, '\n');

        // Catch errors and loop the get input stage until proper input has been entered
        while (!isAlphaStr(firstName) || !(strlen(firstName) > 1))
        {
            cout << "\nError: invalid input, please try again.\n";
            cout << " Hint: only use alphabetical characters.\n";

            cout << "\nEnter your first name: ";
            cin >> setw(16) >> firstName;
            cin.ignore(1000, '\n');
        }

        // Once we've gotten a proper response to the first question, continue
        cout << "Enter your last name: ";
        cin >> setw(16) >> lastName;
        cin.ignore(1000, '\n');

        // Catch errors and loop the get input stage until proper input has been entered
        while (!isAlphaStr(lastName) || !(strlen(lastName) > 1))
        {
            cout << "\nError: invalid input, please try again.\n";
            cout << " Hint: only use alphabetical characters.\n";

            cout << "\nEnter your last name: ";
            cin >> setw(16) >> lastName;
            cin.ignore(1000, '\n');
        }

        // Once we've gotten a proper response to the second question, continue
        cout << "Enter your age: ";
        cin >> setw(4) >> age;
        cin.ignore(1000, '\n');

        // Catch errors and loop the get input stage until proper input has been entered
        while (!isWholeNum(age) || !(atoi(age) > 0))
        {
            cout << "\nError: invalid input, please try again.\n";
            cout << " Hint: only use positive, whole numbers.\n";

            cout << "\nEnter your age: ";
            cin >> setw(4) >> age;
            cin.ignore(1000, '\n');
        }

        // Once we've gotten a proper response to the last question, continue
        cout << "\nGreetings, " << firstName << " " << lastName << " (" << age << ")\n";

        cout << "\nRun the program again? y/n? ";
        cin.get(a);
        cin.ignore();
    }
    while (tolower(a) == 'y');
    return 0;
}

// Determines if user input is a positive whole number
bool isWholeNum (char cArray[])
{
    unsigned short index = 0;

    while(cArray[index] != '\0')
    {
        if (!isdigit(cArray[index]))
            return false;
        ++index;
    }

    return true;
}

// Determines if user input is a string of nothing but alphabetical characters
bool isAlphaStr (char cArray[])
{
    unsigned short index = 0;

    while(cArray[index] != '\0')
    {
        if (!isalpha(cArray[index]))
            return false;
        ++index;
    }

    return true;
}