automate console input in C++ - c++

Question

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.

Answer 1

Usually, this is achieved through standard file descriptor overrides (which name I came up with on the spot and might be different depending on who's talking).
Considering most online compilers probably run on Linux sessions, they can simply do the following.
Build your single-file solution using (for instance) gcc -o venkysmarty-exo-3
Execute it, but override stdin to be a desired file (e.g. ./venkysmarty-exo-3 < ./test_data/exo-3/input.txt)
More generally, on most unix system and at least while running bash, the > operator can be used to redirect standard output, and < to redirect standard input. If not using file name but opened file/pipe descriptor, prefix the descriptor with & (e.g. python max.py <&64, where 64 is the file descriptor.)
On windows, in batch, the file-descriptor thing probably doesn't work, but basic >, < and >> operators seem to work the same:

Answer 2

So I'll answer your question 2 ways. First way, instead of asking for a value using
cin >> a
you can use
int main(int argc, char *argv[])
as your inputs in Visual Studio and to do that You go to Debug, "project name" properties, and then go to debugging. You should see something called command arguments and you can put whatever input you want in there.
The second way to do "automated" input is to put all of your input values in a file. From there you can open the file and read the values from the file. If you don't know how to read and write to a file I recommend using this link here.
http://www.cplusplus.com/doc/tutorial/files/

Answer 3

This solution is for Visual Studio
Have your input in a text file. On the command line redirect the input from this file.
To specify the input, set up the command line
Get Project > Properties
Under configuration properties, select debugging, then edit Command Arguments
e.g. Test input file at "C:\Projects\test.txt"
Edit command line to read "< C:\Projects\test.txt" (Without quotes