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Issue with getline() and cin..

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Join Date: Jun 2007

Posts: 57

Reputation: Run.[it] is an unknown quantity at this point

Solved Threads: 1

Run.[it]

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Junior Poster in Training

Issue with getline() and cin..

May 23rd, 2008

Im trying to carry out input validation on a piece of code and have come across an issue.

Basically for the 1st input I used getline for the string and then for the 2nd input I use cin for the integer. I am aware you can convert the integer from a string with getline but I wish to use the validation underneath to cover for the fact that a user may enter a string instead of the required integer.

When this code runs the second revolution of the For Loop it fires out the first two requests without waiting for user input. I suspect its the clash with getline and cin but Im unsure how to resolve except for using getline which nullifies the validation code.

Any ideas?
If you need any more clarification on my long winded, tedious problem just ask.

Cheers.

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
 
int main ()
{
 
	int n,x,numb;
	string mystr;
 
	for (n=0; n<N_TEAMS; n++)
	{
		cout << "Enter Seeded Team League : ";
		getline (cin,seeded[n].stdetails.league, '\n');
		cin.clear();
 
		cout << "Enter Seeded Team League Placing : ";
		cin >> seeded[n].stdetails.numb;
 
		cin.ignore(numeric_limits<int>::max(), '\n');
 
 
 
		if (!cin || cin.gcount() != 1)
		{
		cout << "Not a numeric value.";
		cin.ignore(numeric_limits<int>::max(), '\n');
		}
 
		else
		{
		cout << "Your entered number: " << seeded[n].stdetails.numb <<endl;
		cin.ignore(numeric_limits<int>::max(), '\n');
		}
 
 
 
		cout <<"\n";
		system("Pause");
		system("cls");
 
 
	}
 
	for (n=0; n<N_TEAMS; n++)
	{
	cout << "League is " << seeded[n].stdetails.league << endl;
	cout <<"\n";
	cout << "Numb is " << seeded[n].stdetails.numb << endl;
	system("Pause");
	cout <<"\n";
	}
}
int main ()
{
 	
	int n,x,numb;
	string mystr;
	
	for (n=0; n<N_TEAMS; n++)
	{
		cout << "Enter Seeded Team League : ";
		getline (cin,seeded[n].stdetails.league, '\n');
		cin.clear();

		cout << "Enter Seeded Team League Placing : ";
		cin >> seeded[n].stdetails.numb;

		cin.ignore(numeric_limits<int>::max(), '\n');



		if (!cin || cin.gcount() != 1)
		{
		cout << "Not a numeric value.";
		cin.ignore(numeric_limits<int>::max(), '\n');
		}
 
		else
		{
		cout << "Your entered number: " << seeded[n].stdetails.numb <<endl;
		cin.ignore(numeric_limits<int>::max(), '\n');
		}

		
	
		cout <<"\n";
		system("Pause");
		system("cls");
	

	}

	for (n=0; n<N_TEAMS; n++)
	{
	cout << "League is " << seeded[n].stdetails.league << endl;
	cout <<"\n";
	cout << "Numb is " << seeded[n].stdetails.numb << endl;
	system("Pause");
	cout <<"\n";
	}
}

.........scaricamento.........

•

Join Date: Oct 2007

Posts: 1,953

Reputation: Duoas has much to be proud of

Solved Threads: 214

Duoas

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Posting Virtuoso

Re: Issue with getline() and cin..

May 23rd, 2008

You are screwing-up your gcount() by using ignore(). Get the count first, then ignore.

Hope this helps.

•

Join Date: Jun 2007

Posts: 57

Reputation: Run.[it] is an unknown quantity at this point

Solved Threads: 1

Run.[it]

Offline

Junior Poster in Training

Re: Issue with getline() and cin..

May 23rd, 2008

•

Originally Posted by Duoas

You are screwing-up your gcount() by using ignore(). Get the count first, then ignore.

Hope this helps.

Yep you are spot on, cheers.

I was close to figuring it as I had placed cin.clear(); after the ignore and it started to work, wasnt sure why though and youve cleared (no pun intended) that up.

Thanks again! 'Solved'

.........scaricamento.........

•

Join Date: Oct 2007

Posts: 1,953

Reputation: Duoas has much to be proud of

Solved Threads: 214

Duoas

Offline

Posting Virtuoso

Re: Issue with getline() and cin..

May 23rd, 2008

It would be just as easy, and permit multi-digit numbers, to input as a string and convert it...

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <algorithm>
#include <cctype>
#include <functional>
#include <sstream>
#include <string>
using namespace std;
int main()
  {
  string s;
  int n;
  cout << "Please enter a number> ";
  getline( cin, s );
  if (find_if( s.begin(), s.end(), not1(ptr_fun<int,int>(isdigit)) ) != s.end())
    {
    cout << "That's not a number.\n";
    }
  else
    {
    stringstream( s ) >> n;
    cout << "You entered the number " << n << endl;
    }
  cout << "Have a nice day!\n";
  return EXIT_SUCCESS;
  }
#include <algorithm>
#include <cctype>
#include <functional>
#include <sstream>
#include <string>
using namespace std;
int main()
  {
  string s;
  int n;
  cout << "Please enter a number> ";
  getline( cin, s );
  if (find_if( s.begin(), s.end(), not1(ptr_fun<int,int>(isdigit)) ) != s.end())
    {
    cout << "That's not a number.\n";
    }
  else
    {
    stringstream( s ) >> n;
    cout << "You entered the number " << n << endl;
    }
  cout << "Have a nice day!\n";
  return EXIT_SUCCESS;
  }