String input problem

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String input problem

 
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  #1
Oct 19th, 2009
Hi, i am new in c++. I am doing an assignment where I need a menu for user to select the operation.

My menu coding is as below.
C++ Syntax (Toggle Plain Text) 
  1. int main()
  2. {
  3.     myCarSystem b;
  4.     char ch;
  5.     string temp1, temp2;
  6.     double temp3, temp4;
  7.     while(1)
  8.     {
  9.        cout<<endl<<endl;
  10.        cout<<" My Car System Operations "<<endl;
  11.        cout<<" ----------------------------- "<<endl;
  12.        cout<<" 1. Insertion/Creation "<<endl;
  13.        cout<<" 2. In-Order Traversal "<<endl;
  14.        cout<<" 3. Removal "<<endl;
  15.        cout<<" 4. Exit "<<endl;
  16.        cout<<" Enter your choice : ";
  17.        cin>>ch;
  18.        switch(ch)
  19.        {
  20.            case 1 : cout<<" Enter car model to be inserted : " <<endl;
  21.                     fflush(stdin);
  22.                     getline(cin, temp1);
  23.                     cout<<"\n Enter car colour type : "<<endl;
  24.                     fflush(stdin);
  25.                     getline(cin, temp2);
  26.                     cout<<"\n Enter car price : "<<endl;
  27.                     fflush(stdin);
  28.                     cin>>temp3;
  29.                     cout<<"\n Enter car deposit : "<<endl;
  30.                     fflush(stdin);
  31.                     cin>>temp4;
  32.                     b.insert(temp1, temp2, temp3, temp4);
  33.                     break;
  34.            case 2 : cout<<endl;
  35.                     cout<<" In-Order Traversal "<<endl;
  36.                     cout<<" -------------------"<<endl;
  37.                     b.print_inorder();
  38.                     break;
  39.            case 3 : cout<<" Enter data to be deleted : ";
  40.                     cin>>temp1;
  41.                     b.remove(temp1);
  42.                     break;
  43.            case 4 : system("pause");
  44.                     return 0;
  45.                     break;
  46.        }
  47.     }
  48.  
  49.     return 0;
  50. }

My problem is, when user is selects the operation, like example user selects 1 to enter car information, the screen will jump back to the menu and skip the input information part.
please help me to check this problem.
Thank you.
Cjjack88.
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  #2
Oct 19th, 2009
Try adding a cin.ignore(); statement before each of your inputs.

See this: http://www.cplusplus.com/reference/i...stream/ignore/

Incidentally, its better you don't use fflush(stdin); . See here for more info.
Last edited by amrith92; Oct 19th, 2009 at 3:56 pm.
"C++ : Where friends have access to your private members."
C++: You accidentally create a dozen instances of yourself and shoot them all in the foot. Providing emergency medical assistance is impossible since you can't tell which are bitwise copies and which are just pointing at others and saying, "That's me, over there."
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  #3
Oct 19th, 2009
Thank you for reply.

I add cin.ignore();, but the problem still occur.
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  #4
Oct 19th, 2009
C++ Syntax (Toggle Plain Text) 
  1. int main()
  2. {
  3.     myCarSystem b;
  4.     char ch;
  5.     string temp1, temp2;
  6.     double temp3, temp4;
  7.     while(1)
  8.     {
  9.        cout<<endl<<endl;
  10.        cout<<" My Car System Operations "<<endl;
  11.        cout<<" ----------------------------- "<<endl;
  12.        cout<<" 1. Insertion/Creation "<<endl;
  13.        cout<<" 2. In-Order Traversal "<<endl;
  14.        cout<<" 3. Removal "<<endl;
  15.        cout<<" 4. Exit "<<endl;
  16.        cout<<" Enter your choice : ";
  17.        cin>>ch;
  18.        switch(ch)
  19.        {
  20.            case 1 : cout<<" Enter car model to be inserted : " <<endl;
  21.                     fflush(stdin);
  22.                     cin.ignore(256, ' ');
  23.                     getline(cin, temp1);
  24.                     cout<<"\n Enter car colour type : "<<endl;
  25.                     fflush(stdin);
  26.                     cin.ignore(256, ' ');
  27.                     getline(cin, temp2);
  28.                     cout<<"\n Enter car price : "<<endl;
  29.                     fflush(stdin);
  30.                     cin.ignore();
  31.                     cin>>temp3;
  32.                     cout<<"\n Enter car deposit : "<<endl;
  33.                     fflush(stdin);
  34.                     cin.ignore();
  35.                     cin>>temp4;
  36.                     b.insert(temp1, temp2, temp3, temp4);
  37.                     break;
  38.            case 2 : cout<<endl;
  39.                     cout<<" In-Order Traversal "<<endl;
  40.                     cout<<" -------------------"<<endl;
  41.                     b.print_inorder();
  42.                     break;
  43.            case 3 : cout<<" Enter data to be deleted : ";
  44.                     cin>>temp1;
  45.                     b.remove(temp1);
  46.                     break;
  47.            case 4 : system("pause");
  48.                     return 0;
  49.                     break;
  50.        }
  51.     }
  52.  
  53.     return 0;
  54. }
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  #5
Oct 19th, 2009
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Originally Posted by amrith92 View Post
Try adding a cin.ignore(); statement before each of your inputs.

See this: http://www.cplusplus.com/reference/i...stream/ignore/

Incidentally, its better you don't use fflush(stdin); . See here for more info.
C++ Syntax (Toggle Plain Text) 
  1. int main()
  2. {
  3.     myCarSystem b;
  4.     char ch;
  5.     string temp1, temp2;
  6.     double temp3, temp4;
  7.     while(1)
  8.     {
  9.        cout<<endl<<endl;
  10.        cout<<" My Car System Operations "<<endl;
  11.        cout<<" ----------------------------- "<<endl;
  12.        cout<<" 1. Insertion/Creation "<<endl;
  13.        cout<<" 2. In-Order Traversal "<<endl;
  14.        cout<<" 3. Removal "<<endl;
  15.        cout<<" 4. Exit "<<endl;
  16.        cout<<" Enter your choice : ";
  17.        cin>>ch;
  18.        switch(ch)
  19.        {
  20.            case 1 : cout<<" Enter car model to be inserted : " <<endl;
  21.                     cin.ignore();
  22.                     getline(cin, temp1);
  23.  
  24.                     cout<<"\n Enter car colour type : "<<endl;
  25.                     cin.ignore();
  26.                     getline(cin, temp2);
  27.  
  28.                     cout<<"\n Enter car price : "<<endl;
  29.                     cin.ignore();
  30.                     cin>>temp3;
  31.  
  32.                     cout<<"\n Enter car deposit : "<<endl;
  33.                     cin.ignore();
  34.                     cin>>temp4;
  35.  
  36.                     b.insert(temp1, temp2, temp3, temp4);
  37.                     break;
  38.            case 2 : cout<<endl;
  39.                     cout<<" In-Order Traversal "<<endl;
  40.                     cout<<" -------------------"<<endl;
  41.                     b.print_inorder();
  42.                     break;
  43.            case 3 : cout<<" Enter data to be deleted : ";
  44.                     cin>>temp1;
  45.                     b.remove(temp1);
  46.                     break;
  47.            case 4 : system("pause");
  48.                     return 0;
  49.                     break;
  50.        }
  51.     }
  52.  
  53.     return 0;
  54. }

The problem still same.
Anyway thank you for the information.
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  #6
Oct 19th, 2009
If cin.ignore(); fails, then try clearing the input stream, before accepting input. This can be done with cin.clear(); .

If all your inputs are failing, then maybe try the following:

1. Clear the input stream.
2. Read the rest of the characters in the stream into a temporary string.
3. Accept the user's input

So, for example, the statements to do this might be:
C++ Syntax (Toggle Plain Text) 
  1.         cin.clear();
  2.         string rubbish;
  3.         cin >> rubbish;
"C++ : Where friends have access to your private members."
C++: You accidentally create a dozen instances of yourself and shoot them all in the foot. Providing emergency medical assistance is impossible since you can't tell which are bitwise copies and which are just pointing at others and saying, "That's me, over there."
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1
  #7
Oct 19th, 2009
Before worrying about big things please pay some attention towards small things...
There is a lot of difference between 1 and '1' .
The input you are taking is a character so the cases of switch should be as case '1' : case '2' : and all , else make the input to be taken to a integer rather than a character.

And ya usage of fflush(stdin) is bad. One more point of concern is all the inputs you are taking doesn't actually need a space and hence you don't even need to use getline().You can directly use cin >> temp1;
4 posts without even concentrating on the main problem.This way you will add all the statements in this world but still wont be able to take the inputs.
Last edited by csurfer; Oct 19th, 2009 at 4:25 pm.
I Surf in "C"....
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  #8
Oct 19th, 2009
I found where is the problem. I did a careless mistake.
amrith92 , thank you for your help and informations.
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  #9
Oct 19th, 2009
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Originally Posted by csurfer View Post
Before worrying about big things please pay some attention towards small things...
There is a lot of difference between 1 and '1' .
The input you are taking is a character so the cases of switch should be as case '1' case '2' and all , else make the input to be taken to a integer rather than a character.

And ya usage of fflush(stdin) is bad. One more point of concern is all the inputs you are taking doesn't actually need a space and hence you don't even need to use getline().You can directly use cin >> temp1;
Thank you for reply. I did a careless mistake.
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