Any C++ pros out there?

"If only EssExTee could be so grossly incandescent" (essextee) 08/31/2014 at 01:36 • Filed to: None

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I'm re-teaching myself after a ~2 year break and I'd love to pick your brain for help with a program I'm writing.

mcseanerson > If only EssExTee could be so grossly incandescent 08/31/2014 at 01:43

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Wish I could help but I still haven't learned the first time. Re-learning sucks because your reading through and it's like 30 pages of I know that and when you're finally tired of reading every single sentence you skip a little bit and then miss the one thing that is either new or you didn't remember. I do not envy you.

Tim (Fractal Footwork) > If only EssExTee could be so grossly incandescent 08/31/2014 at 01:45

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I'm in the same boat as you, but what is your question anyhow? I don't know if I can help, but perhaps...

Nate Bleker > If only EssExTee could be so grossly incandescent 08/31/2014 at 01:45

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I might be a bit drunk but I do c++ for a living. Whatcha got?

If only EssExTee could be so grossly incandescent > Nate Bleker 08/31/2014 at 01:55

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Well, let's say the program is waiting on input from the user. The input options are 1 and 2. If the user types those numbers, the program continues, but if anything else is input the program quits. What can I do so that if a "wrong" input is given, the request for input is repeated?

ToyDeathbot > If only EssExTee could be so grossly incandescent 08/31/2014 at 02:09

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can't you use a 'while' loop to constantly check if the input is false?

If only EssExTee could be so grossly incandescent > ToyDeathbot 08/31/2014 at 02:33

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I'm getting some super weird error messages when trying to use it, such as "variable is being used without being initialized". Do I have to initialize it within the loop, as well as before my main()?

ToyDeathbot > If only EssExTee could be so grossly incandescent 08/31/2014 at 02:50

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I'm not particularly familiar with C++, but in general, the layout should be something like this.

User inputs something (let's say x) <- This is where I think your error came from
while x > 2 | x == 0
give some sort of error message and tell the user to re-input x value
end

and then if it is option 1 or 2, it continues onwards

ToyDeathbot > If only EssExTee could be so grossly incandescent 08/31/2014 at 03:00

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here's something I've done real quick on MATLAB (it's way easier to understand than C++)

If only EssExTee could be so grossly incandescent > ToyDeathbot 08/31/2014 at 03:02

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Fucking MATLAB...

*grumbles*

ToyDeathbot > If only EssExTee could be so grossly incandescent 08/31/2014 at 03:21

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haha, that's what everyone says

Pockets > If only EssExTee could be so grossly incandescent 08/31/2014 at 06:47

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When you say "initialising before main()", that sounds kinda dodgy - is it declared but not initialised at that point, then only gets initialised within the loop, which would mean on the first iteration it would fail like this? Post a snippet.

crowmolly > If only EssExTee could be so grossly incandescent 08/31/2014 at 08:38

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Probably happening if you are using a while loop without giving the variable an initial value.

If you say

while (x != 0)

{

}

it won't work unless you do something like

int x = 9999;

while (x != 0)
{

}

In the first case, x will be filled with whatever shit currently resides in the memory address that was just given to x. It could be anything at that point.

Or you could use a do/while loop. In that case the condition is checked at the END of the loop so the inner code (where you probably assign a value to the variable giving you trouble).

zeontestpilot > If only EssExTee could be so grossly incandescent 08/31/2014 at 09:36

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Um, I use Java, and haven't touched C++ in a while. I know in Java, you have to initialize the variable before the loop, at least if you want to use it out side of it. This is a mix of java & C++, so....

int x = 0;

while (true) {

if (x == 1) { break; }

else if (x == 2 ) { break; }

else { cout << "Incorrect input, try again." }

} // end while loop.

You could mske the if statement like "if( x==1 || x ==2 )", but if you give it just one statement to check, its more of a boolean statement and should run faster (better on bigger programs).

Can you post your code so we can see what you have so far?

 > If only EssExTee could be so grossly incandescent 08/31/2014 at 10:46

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I will give you one tip that will save your ass every time. Don't forget a semicolon.

Lol ok that's all I got. I hate programming but can do it if I have to.

 > ToyDeathbot 08/31/2014 at 10:50

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That looks like c#, not c++. In c++ you have to initialize the variable before you can use it.

it would be something like

int x;

Assuming x is an integer. You can read on variables here, http://www.cplusplus.com/doc/tutorial/v…

Tim (Fractal Footwork) > If only EssExTee could be so grossly incandescent 08/31/2014 at 11:54

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Don't you have to put in an else at the end?

if, logical statement if a

else if, logical statement if b

else, logical statement if not either a or b

If only EssExTee could be so grossly incandescent > crowmolly 08/31/2014 at 12:00

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The variable is declared at the beginning already. That's why the error message makes no sense.

If only EssExTee could be so grossly incandescent > Pockets 08/31/2014 at 12:03

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Problem is, the code works perfectly fine without the loop, but the moment I add the do{}while it stops working.

crowmolly > If only EssExTee could be so grossly incandescent 08/31/2014 at 16:10

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Declared AND initialized?

If only EssExTee could be so grossly incandescent > crowmolly 08/31/2014 at 21:43

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The variable's value is created by input from the user, there is no initial value. The do while loop is supposed to allow for that but it's not.