CODEWITHSUNDEEP
c++
Jack F
Jack F

Reputation: 553

replacing an element value in a vector

so i am doing a inventory program. I have a vector of class items in it and I want to user enter Id and then run an iterator to match with the Id that is in the vector and change the value of the quantity sold:

here is part of my code:

 vector<Item>::const_iterator it;
  for(it=items.begin(); it !=items.end(); it++){
    if (it->getID() == id){
      amount=it->getactual()-sold;
      it->setactual(amount);

that is in my class

int getactual()const{return actual_quantity;}
void setactual(int quantity){actual_quantity=quantity;}

but i get an error: passing ‘const Item’ as ‘this’ argument of ‘void Item::setactual(int)’ discards qualifiers

Upvotes: 0

Views: 89

Answers (3)

billz
billz

Reputation: 45410

You should use 

vector<Item>::iterator

instead of 

vector<Item>::const_iterator

const_iterator means read-only.

Upvotes: 1

Matteo Italia
Matteo Italia

Reputation: 126777

setactual obviously cannot operate on a const object (as the one that you obtain via a const_iterator; change const_iterator to plain iterator.

Upvotes: 1

imreal
imreal

Reputation: 10348

The problem is that you are using a const iterator but you are modifying what it points to (calling non-const members), try using a regular iterator:

vector<Item>::iterator it;

Upvotes: 1

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