stuck with getline() function

This is a discussion on stuck with getline() function within the C++ Programming forums, part of the General Programming Boards category; below are a part of my program ... the problem here is ... when i run the 1st option (1. ...

  1. #1
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    stuck with getline() function

    below are a part of my program ... the problem here is ... when i run the 1st option (1. Open an account) ... it display my cout ... but skipped my cin ...

    Code:
    #include <iostream>
    #include <string>
    #include <iomanip>
    
    using namespace std;
    
    class acc
    {
    	public:
    		void initial();
    		void deposit();
    		void withdraw();
    		void display();
    
    	private:
    		string name;
    		int accno;
    		string type;
    		float balance;
    };
    
    void acc::initial()
    {
    	cout << "Name: ";
    	getline(cin, name);
    	cout << "Account No: ";
    	cin >> accno;
    	cout << "Account type: ";
    	cin >> type;
    	cout << "Initial amount: ";
    	cin >> balance;
    }
    
    void acc::deposit()
    {
    	float dep;
    	cout << "Deposit: ";
    	cin >> dep;
    	balance += dep;
    }
    
    void acc::withdraw()
    {
    	float draw;
    	cout << "Withdraw: ";
    	cin >> draw;
    	if(balance < draw)
    		cout << "Insufficient amount in your balance" << endl;
    	else
    		balance -= draw;
    }
    
    void acc::display()
    {
    	cout << "Name: " << name << endl;
    	cout << "Account No.: " << accno << endl;
    	cout << "Account Type: " << type << endl;
    	cout.setf(ios::fixed);
    	cout << "Balance: " << setprecision(2) << balance << endl;
    }
    
    int main()
    {
    	system("color 1F");
    
    	acc x;
    	int option;
    
    	while(true)
    	{
    		cout << "\t\t\t1. Open an account" << endl;
    		cout << "\t\t\t2. Deposit money" << endl;
    		cout << "\t\t\t3. Withdraw money" << endl;
    		cout << "\t\t\t4. Show info" << endl;
    		cout << "\t\t\t5. Exit\n" << endl;
    		cout << "\t\t\tChoose an option: ";
    		cin >> option;
    
    		switch(option)
    		{
    			case 1:
    				cout << "\n";
    				x.initial();
    				system("pause");
    				system("cls");
    				break;
    
    			case 2:
    				cout << "\n";
    				x.deposit();
    				system("pause");
    				system("cls");
    				break;
    
    			case 3:
    				cout << "\n";
    				x.withdraw();
    				system("pause");
    				system("cls");
    				break;
    
    			case 4:
    				cout << "\n";
    				x.display();
    				system("pause");
    				system("cls");
    				break;
    
    			case 5:
    				exit(1);
    		}
    	}
    
    	return 0;
    }
    anyone mind to explain to me ?

  2. #2
    Registered User major_small's Avatar
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    try this:
    Code:
    void acc::initial()
    {
    	cout << "Name: ";
            cin.ignore(1); //skips what's left in the input stream
    	getline(cin, name);
    	cout << "Account No: ";
    	cin >> accno;
    	cout << "Account type: ";
    	cin >> type;
    	cout << "Initial amount: ";
    	cin >> balance;
    }
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  3. #3
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    why add ignore function ? mind to explain ? i am still new to C++

    Code:
    cin.ignore(1);
    beside that, is there any other way to replace/modfy the getline function so

    Code:
    getline(cin, name);
    i don't have to press enter TWICE after i entered the value for the variable name. Instead, i just have to press enter ONCE like i enter values for other variables.

  4. #4
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    isnt thier suppose to be a period in getline?

  5. #5
    Registered User jlou's Avatar
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    The press enter twice thing might be a bug in the STL implementation used by Visual C++ 6.0. Check out this site and scroll down to the part about <string>

    http://www.dinkumware.com/vc_fixes.html

    or look at this one

    http://support.microsoft.com/default...;en-us;Q240015

    Once you apply their fix, you can use getline like you wanted to.

  6. #6
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    sure, don't use >> in the same program as getline(). Otherwise you can't avoid the problem. The fix isn't all that hard. Once you have enough experience and learn how >> and getline() actually work under the hood you'll be better able to appreciate the reason this is as it is. For now, just remember that if you use getline() you should (probably) call ignore() just before the call to getline(), especiallly when using >> and getine() in the same program. As an aside, I might use a different set of parameters for ignore() than was suggested, but that's neither here nor there right now. The point is use the combination of ignore() and getline().

  7. #7
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    instead of using getline() function, is there any other way to input a line of characters into string ?

  8. #8
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    Code:
    	else if (_Tr::eq((_E)_C, _D))
                    {_Chg = true;
                  //  _I.rdbuf()->snextc(); /* Remove this line and add the  line below.*/ 
    		  _I.rdbuf()->sbumpc();
                    break; }
    i opened string.h in the include folder but i cant find the code as mentioned above ....

    mind telling me how to fix the bug ?

  9. #9
    Registered User jlou's Avatar
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    Originally posted by stalker
    i opened string.h in the include folder but i cant find the code as mentioned above ....

    mind telling me how to fix the bug ?
    The file is string, not string.h. If you still can't find it then maybe you don't have that bug (which would be strange if you are using VC++ 6.0). Search for getline in the file, and then search for snextc in that function.

  10. #10
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    thanks jlou ....... i found it ~

  11. #11
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    thanks elad for your help ~

  12. #12
    Registered User major_small's Avatar
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    Originally posted by stalker
    instead of using getline() function, is there any other way to input a line of characters into string ?
    yeah, but it stops at whitespaces...
    Code:
    cin>>fname>>lname;
    cout<<fname<<' '<<lname;
    //input: My Name
    //output: My Name
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  13. #13
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    Getline under the hood

    Problems with getline(cin, name);

    Since getline does not ignore leading whitespace characters, you should take special care when using it in conjunction with cin >>.

    The problem: cin>> leaves the newline character (\n) in the iostream. If getline is used after cin>>, the getline sees this newline character as leading whitespace, thinks it is finished and stops reading any further.

    Program fragment with problem:

    string name;
    int age;

    cout<<"Enter your age";
    cin>>age;
    cout<<"Enter your full name";
    getline(cin, name);

    cout<<name<<", you are "
    <<age<<endl;
    OUTPUT:
    Enter your age 5
    Enter your full name Ben Bunny
    , you are 5
    The name did not print because the getline saw the newline character left from the cin>> as whitespace and stopped reading any further.

    So , bottom line you have to learn when things are left in the iostream.........& when they're not.
    In addition to cin.ignore ...you could also use flush or endl..........both of these flush the \n out of the iostream........
    Hope that helps to understand why...........

  14. #14
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    flush and endl clear the ostream buffer, but not the istream buffer.

  15. #15
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    Arrow

    elad
    My Bad ..Thanks for straighting that out..........I learn something everyday around here........ ....
    Is cin.ignore the only way to deal with using cin in conjunction with getline then?
    Last edited by teeyester; 10-24-2003 at 07:28 AM.

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