clear ctrl-z from buffer

[grcunning]

I'm having a problem with our assignment this week.
What I have is a function that has the user enter data into several parallel arrays(name,age,gender,gpa). Since we don't know ahead of time how many entries
there will be, the assignment says to use:
"Press ctrl-z to quit", and then the function exits. this part works fine.
Now we have to ask the user which field he would like to sort on, and then use
a bubble sort to display the data sorted on the requested field.
The problem I am having is that after the data is entered(then a ctrl-z),
I display the menu asking which field to sort on.
The computer completely skips the cin command, I am pretty sure because
the ctrl-z is still in the buffer. If I drop the capacity(max size of the array)
down to 3 or 4, and then fill the array, the function exits without the
ctrl-z, and everything else works fine, including the sort.
cin.ignore() doesn't work either.
This is the function:

void getData(string names[],int ages[], char genders[], double gpas[], int capacity,int &n)
{

	string name;
	
	cout << "enter the first name please" << endl;
	while (cin>>name)
	{
		names[n]=name; //place value into array
		cout << "enter " << name << "'s age :";
		cin >> ages[n];
		cout << "enter " << name << "'s gender (M/F) :";
		cin >> genders[n];
		cout << "enter " << name << "'s gpa :";
		cin >> gpas[n];
		n+=1; //increment number of values
		if (n<capacity)
			cout << "enter next name, ctrl-z to quit " << endl;
		else
			{
			cout << "array is full, no more ages allowed"<< endl;
			system("pause");
			break;
			}//else
	}//while
}//getData 

And this is the section of code that should get input from the keyboard

        getData(names,ages,genders,gpas,SIZE,n);
	cout << "The unsorted values are:\n";
	showArray(names,ages,genders,gpas,n);
	cout << endl;
	while (true)
	{
		cout << endl << "How would you like the data sorted?" << endl;
		cout << "1) By age" << endl;
		cout << "2) By name" << endl;
		cout << "3) By gender" << endl;
		cout << "3) By gpa" << endl;
		cin.ignore();
		cin.get(sortType);
		switch (sortType)
		{
			case '1' :
				sortArray(ages,names,genders,gpas,n);
				break;
			case '2' :
				sortArray(names,ages,genders,gpas,n);
				break;
			case '3' :
				sortArray(genders,ages,names,gpas,n);
				break;
			case '4' :
				sortArray(gpas,names,ages,genders,n);
				break;
				
		} //switch
		showArray(names,ages,genders,gpas,n);
		system("pause");

When stepping through, the cin (and I also tried cin >> sortType) gets skipped
and it drops out of the switch(I haven't bothered to put a default case
in there yet.

Any ideas?

[Zaita]

http://www.cplusplus.com/forum/articles/6046/ might be of use for you.

[firedraco]

I think the reason why it is exiting is because ctrl+z is giving cin an error state...you will need to call cin.clear() to clear the error state. Although I would suggest putting the data into something like a string, then check for the character combo manually, I suppose you could do it the way you are.

[grcunning]

cin.clear() worked..thanks

hey Zaita...I've had alot of problems with data validation, like when I ask for a number and the user enters a string.
I like this

int myNumber = 0;

 while (true) {
   cout << "Please enter a valid number: ";
   getline(cin, input);

   stringstream myStream(input);
   if (myStream >> myNumber)
     break;
   cout << "Invalid number, please try again" << endl;
 }
 cout << "You entered: " << myNumber << endl << endl;

but Im not sure how it works. Is there a simple explanation? I read the stringstream reference page, but I'm still confused how this line works:

if (myStream >> myNumber)

[Zaita]

myStream >> myNumber Is an overload and equal to istream& myStream.convertTo(int& val );.

It'll try and format the contents of myStream into an int to store in myNumber. If this is successful it'll return the address of myStream. If this fails it'll return NULL (0).

if (NULL) = false; so if it fails then your if statement fails.