Add multiple data in a std::set using +=operator

This is a discussion on Add multiple data in a std::set using +=operator within the C++ Programming forums, part of the General Programming Boards category; hi can anyone tel me how to insert multiple data at once in a std::set using an +=operator? i've created ...

  1. #1
    Registered User IndioDoido's Avatar
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    Add multiple data in a std::set using +=operator

    hi

    can anyone tel me how to insert multiple data at once in a std::set using an +=operator?

    i've created this function to insert a product into a set, but i don't know how to use an +=operator :-(

    Code:
    void grocery::insertProducts()
    {
    	set <product> Prod;
    
    	string typeP, detalP, idP;
    	unsigned int costP;
    
    
    	cout<<"\n Type: ";
    	getline(cin,typeP);
    	fflush(stdin);
    
    	cout<<"\n Detailes: ";
    	getline(cin,detalP);
    	fflush(stdin);
    	
    	cout<<"\n Cost: ";
    	cin>>costP;
    
    	cout<<"\n Product ID: ";
    	getline(cin,idP);
    
    	product insertProd(typeP, detalP, costP, idP);
    
    	Prod.insert(insertProd);
    }
    can anyone help?
    "Artificial Intelligence usually beats natural stupidity."

  2. #2
    The larch
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    Overload the += operator for grocery. Something like:
    Code:
    void grocery::operator+= (const product& p)
    {
        mySet.insert(p);
    }
    (I'm not sure if this is good use for operator overloading. A function name conveys more information about what to expect from it.)

    Note that in your existing code the set is local to the method and disappears when the function exists.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  3. #3
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    You can't use += to add to a set. You use insert instead, which you seem to already be doing.

    A couple other comments about the code:
    1. You created a set call Prod and insert a product into it. But that set is a local variable that is destroyed when the function ends, so you really did nothing. Shouldn't you be inserting into a member variable of the grocery class?
    2. fflush(stdin); is bad and unnecessary. I'm not sure why you think you need it, but I'm pretty sure you don't. Remove it.
    3. You call cin>>costP; and then call getline(cin,idP); just below it. If you use cin>> and getline together, you need to add a cin.ignore() after the cin>> call to ignore the trailing newline. This should only be done after cin>>, not after getline.

  4. #4
    Registered User IndioDoido's Avatar
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    hey Anon

    for the operator to work, i need to insert the code i used in my function ( void grocery::insertProducts(); ) to the new +=operator function ( void grocery:perator+= (const product& p); ), right?
    "Artificial Intelligence usually beats natural stupidity."

  5. #5
    and the hat of sweating
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    Quote Originally Posted by IndioDoido View Post
    hi
    can anyone tel me how to insert multiple data at once in a std::set using an +=operator?
    Use std::set<T>::insert( start, end ) where start is the first element you want to insert and end is the last element to insert (assuming they're in some kind of array or iterable container).

  6. #6
    Registered User IndioDoido's Avatar
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    hi cpjust,
    but i need to use a +=operator :-(
    "Artificial Intelligence usually beats natural stupidity."

  7. #7
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    Do you need to use it on the set (which is not possible) or for your class?

    If you want it for your class, then what do you want to add? I assume you want to add a product, but that means that the code that gets the data for the product from cin must be put somewhere else.

  8. #8
    Registered User IndioDoido's Avatar
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    i have a class product with the elements for each product (price, type, etc...) and i need to create a simple program to insert, search, update and erase products from a set.

    but i must use a +=operator to insert several products at the same time :-(
    "Artificial Intelligence usually beats natural stupidity."

  9. #9
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    Please give more information, perhaps an entire paragraph. Or just answer the questions asked.

    You cannot use += to insert into the standard library's set class.

    What your assignment probably wants is to add an operator+= to the grocery class or some other class that holds multiple Products. It's up to you to tell us if that's true.

  10. #10
    Registered User IndioDoido's Avatar
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    I'm going to try and translate the assignment requirements:

    "The product table must support addictions of new products through a +=operator (supporting multiple addictions at once)."

    Its not easy for me, explaining myself in a different language, sorry.
    Last edited by IndioDoido; 10-31-2007 at 07:30 PM.
    "Artificial Intelligence usually beats natural stupidity."

  11. #11
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    Ok, so that is referring to a "product table", not the standard library std::set class. That's the distinction I wanted to make.

    I'm not sure how you can add multiple products at once. That doesn't make sense to me.

    Do you have a class for your "product table"? Add an operator+= to that class. Use anon's code as an example.

    Hope that makes sense.

  12. #12
    Registered User IndioDoido's Avatar
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    ok, thanks for the help, i'm going to work on that later.

    now i'm trying to find a product using .find(), but it doesn't work :-(

    Code:
    void grocery::findProduct()
    {
    	string id;
    
    	cout<<"Product ID: ";
    	cin>>id;
    
    	set <product>::const_iterator it;
    
    	if( Prod.find(id) == Prod.end() ) //set <product> Prod; is inside the grocery.h
    		cout<<"not found\n";
    	else cout<<"\nthe product type is: "<<it->getType() <<"\n";
    
    	system("pause");
    
    }
    i know the product was inserted because after insertion, i view all products to be certain.
    "Artificial Intelligence usually beats natural stupidity."

  13. #13
    Registered User IndioDoido's Avatar
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    hi Daved!

    thats correct, when i insert a product it has an ID, type, detail and cost.
    i'm going to try that...

    tnx again ;-)
    "Artificial Intelligence usually beats natural stupidity."

  14. #14
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    I moved my post to your new thread... it's a new topic anyway so you can continue to discuss it there. Sorry for the confusion.

  15. #15
    Registered User IndioDoido's Avatar
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    ok...
    no problem ;-)
    "Artificial Intelligence usually beats natural stupidity."

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