Input Validation With Ints and Doubles

So i am trying to have the user only receive integers when they are choosing an array size but the numbers don't add up if I were to to type in a floating number. If they type in letters then the right error message pops up but I can't get right if they type in 4.4, 1.21, etc. the way I currently have it. Am I doing this hard way? Would I be better off using stringstream? I left out a chunk of the code.

#include <iostream>
#include <limits>


int main()
{
const int CAPACITY = 100;
int choice;
int size = 0;
double array[CAPACITY];

    do
    {
    std::cout << "Hey there! Pick an option" << std::endl;
    std::cout << "Hit 1 to do some math " << std::endl;
    std::cout << "Hit 2 to quit" << std::endl;
    std::cin >> choice;

    if (choice == 1)
    {

        std::cout << "Choose the size of your array. The array can be set to capacity of 100" << std::endl;
        //std::cin >> size;

        if((std::cin >> size).fail()) {
            std::cin.clear();
            std::cin.ignore(1000, '\n');
                std::cout << "Invalid input" << std::endl;
                continue;
            }
        if(size <= 0){
            std::cout << "Sorry, that not a valid option" << std::endl;
            continue;
        }
        if (size > CAPACITY){
            std::cout << "Sorry, that is too large" << std::endl;
            continue;
        }
        if (size < CAPACITY){
            std::cout << "Add some numbers to your array" << std::endl;

            for (int i=0; i < size; i++)
            {
                std::cout << "Enter a number: " << std::endl;
                std::cin >> array[i];
            }