automate console input in C++

I am participating in few online programming exercises in C++.

Here problem description is given as to test understanding "for" loop in C++.

Input Format

You will be given two positive integers, a and b (a <=b), separated by a newline.

Output Format

For each integer in the interval [a,b :

If 1 <=n <= 9, then print the English representation of it in lowercase. That is "one" for , "two" for , and so on. Else if n > 9 and it is an even number, then print "even". Else if n > 9 and it is an odd number, then print "odd".

Sample Input

8 11

Sample Output

 eight
 nine
 even
 odd

I have written program as below and test case passed.

int main() {
    int a, b;
    cin >> a;
    cin >> b;
    string num[9] = {"one", "two", "three", "four", "five", "six", "seven",                             "eight", "nine"};

    for(int n=a; n<=b;n++)
    {
        if(n<=9)
            cout << num[n-1] << endl;
        else
            if(n%2==0)
                cout << "even\n";
            else
                cout << "odd\n";
    }
    return 0;
}

While I am testing, I am entering values for "a" and "b".

I can understand when I submit my code online, test cases are executed and results are shown.

My question how input is automated?. I also want to test my code with automation with out entering input at console.

Sample code for automate will be helpful. This understanding will be helpful as I move forward in working on complex problems where more inputs will be required, so I don't want to enter manually at cin from console and want to automate this while i am testing at my laptop, just same as the way online automated test tool is doing.

Thanks for your time and help.