Error when looping over an object array

I have created two classes: a market and a good. I can add goods to market by buying them or I can remove them from my market by selling them. I have written a method buy

1. Every time I buy a good, it checks whether there is such a product in my market, and if yes, it adds the quantity to the existing quantity.

2. If the product does not exist, it adds it as a new object to my good array.

function buy(obj, item)
            exists=0;
            for i=1:length(obj.goods)
                if obj.goods(i).name==item.name
                   obj.goods(i).quantity=obj.goods(i).quantity+item.quantity;
                   exists=1;
                end                     
            end
            if exists==0
                obj.goods(end+1)=item;
            end
        end

First time I call the method it adds the object to the array. Now I have only one object in the array.

Second time I get the following error

>> mymarket.buy(cheese)
Error using  == 
Matrix dimensions must agree.

Error in market/buy (line 17)
                if obj.goods(i).name==item.name

Any help will be appreciated.

Answer 1

[per isakson]

Your code cannot compare names of different lengths

>> 'aaa' == 'bbbb';
Error using  == 
Matrix dimensions must agree. 
>>

Replace

obj.goods(i).name==item.name

by

strcmp( obj.goods(i).name, item.name )