Thread: Problems with cin and GetAsyncKeyState

Well, I'm a beginner in C++ and I tend to make MANY errors when trying out codes I'm not taught before. So recently I got to know about GetAsyncKeyState and i used it in my main function which is basically a menu. I did all the stuff I will need to do for GetAsyncKeyState in a bool keyDown(int vKey) function which returns either 1 or 0 depending on whether the key is pressed.

Now my menu is supposed to link to another file which takes care of the user entering his/her profile. For this page I used cin, but I noticed a bug. This bug is that if I type something on the menu then press Enter to go into the profile page, which would go to the void profile() function, whatever I typed while on the menu page would automatically cin into my first cin, which is very weird. Of course, it would be better if someone could add me on MSN and help me but [if you need to see a part of my code to find out whats causing this problem feel free to post it here.]

Well basically what I meant was that the bool keyDown(int vKey) function would check if a key is pressed. So lets say keyDown(VK_RETURN) would check if VK_RETURN is pressed. So lets say I do something like

Code:

if(keyDown(VK_RETURN))
{
     cout << "Enter!" << endl;
}

the keyDown function would return true if I pressed Enter and then cout Enter right? But now the problem is the string I want the user to cin after the user is done with the menu.

Like

Code:

struct profile
{
     string name;
};
void profilepage(void)
{
     system("cls");
     profile player;
     cout << "Enter your name :";
     cin >> player.name;
void main (void)
{
     cout << "This is the Menu! Press Enter to proceed!" << endl;
     if(keyDown(VK_RETURN))
     {
          profilepage();
     }
}

So if the player presses Enter, he'll go to the "Enter your name :" part right? But the bug now is that, if I press Enter, it would show "Enter you name :" but the blinking _ is on the next line. I found it weird so at the "This is the Menu! Press Enter to proceed!" part I typed lolol before pressing Enter and the moment I press Enter it shows "Enter you name : lolol". Why does this happen? O_O and please remember that I am still a newbie so xD

Well I admit I skimmed through but it was because I didn't get the "consume" part so I thought I had to make things as clear as possible. So anyway, are you talking about the cin buffer thing which cin.clear() clears? and whenever I type anything it would go into the cin buffer?

By default, ignore ignores until the EOF.

As to your question, who knows what you did? (Answer: you, and not us.) What is the loop condition on your infinite loop?

That endless loop is something like THE endless loop that happens when say you cin a char into an int variable. But if you need to see the code,
Here it is!

Code:

struct personProfile
{
	char name[50];
	int age;
	char gender;
};
void profile (void)
{
	int choice;
	personProfile person1;
	
	system("cls");
	cout<<"                         ~~Welcome to Black-O~~"<<endl;
	cout << endl;
		cout<<"Enter Name: ";
		cin.get(person1.name,50,'\n');
.
.
.

No even in a simple code without any loops, this error will also happen.
See Cprogramming.com : FAQ > How do I...(Level 2) > Why does my program enter an infinite loop if the user inputs invalid data? (C++).
I just want to know what I should do to my code that you can see to prevent the user from entering invalid data.

But I used cin.get(person1.name,50,'\n') so why won't it work? If cin.get is significantly different from getline could you tell me how I could use getline to replace cin.get in the code i posted earlier?

getline and get behave the same way. You can only get the infinite loop of bad input you appear to be talking about if you try to read numeric input directly. You can't get an infinite loop on inputting a string or characters.

I'm using cin.get to get a string aren't I? So why does it still error?

Originally Posted by KgNe

I'm using cin.get to get a string aren't I? So why does it still error?

I assume the error is on the very next line after the bit you posted where it says cin >> person1.age. I will continue to believe that until you convince me otherwise. (In other words: I have been completely unable to make the snippet you posted behave in any violent manner.)