With the way you're implementing damage and armor, you'll have to check to see if the damage is less than the armor value.. something like this:

if (character.armor > damage) {
totaldamage = 0;
}
else {
totaldamage = damage - character.armor;
}

This will ensure you don't ever add health to the character in the event that the initial damage is less than the armor value.

As for the timer, I'm not a C# programmer, but you could just have frequent checks throughout the program (after a round of the fight, after a movement to a new location) to peek at the current TIME (in s), and after 5 mins have gone by from the previous timed event, then GiveAilment(). Since this is text-based and probably round-based instead of real-time, having many timer checks through the code won't affect performance..


You just mentioned you're not using any loops? You'll want to learn those now - nearly all programs use them in some fashion.

For example:

Start game
Make/load character
Begin game loop
//game code (travel, etc) until fight happens
Begin fight loop
//fight code
end fight loop when character or monster dies
End game loop when user exits game (dies, logs off, etc)

Quote:
How can I make it so that the totalDamage variable can only equal a positive number?

Write a little method to clamp the damage value between 0 and whatever the maximum is. You could also store the damage as an unsigned type, but beware that you'll get compiler errors related to requiring explicit casts if you do so, and if you perform the casts you'll end up in the same boat. Besides in some cases it may be desirable to allow "negative" damages.

Quote:
The problem with that is I don't know how to make that if statement run every, say, 5 minutes.

Once you have your timer/clock object, ask it for the current time every frame, and use that plus the current time from the last frame to figure out how much time has elapsed. Accumulate and store that elapsed time someplace, and when it is greater than or equal to five minutes, execute the code.

There are built-in timer methods in the .NET frameowkr, but many of them are designed for threading stuff and/or for low-priority repeating events that don't need a lot of accuracy. Often you are better off implementing the timer yourself using lower-level functions (p/invoking QueryPerformanceCounter or timeGetTime are popular). Google for C# timing methods, you'll get a lot of results.