Thread: about inset value in vector

hi everyone this is my solution but there is a problem..

can someone help me on the inserting value into vector of string

Code:

/ insert a value into the set
// Pre: a string value
// Post: the value is inserted into the set if it 
//      is not already present
void StringSet::insert(string value) 
{
     int contentSize = contents.size();
     
     for(int i = 0; i < 4; i++)
     {
             if(contents[i] != value)
                  contents.push_back(value);     
     }      
}

this is the header file

Code:

using namespace std;
// StringSet
//  Class holding a set of strings
class StringSet 
{
 private: 

  vector <string> contents;
 
 public:

  // insert a value into the set
  // Pre: a string value
  // Post: the value is inserted into the set if it 
  //      is not already present
  void insert(string value);
  
  // test for a value
  // Pre: a string value
  // Post: returns 1 if the value is present in the StringSet, 0 otherwise
  int contains(string value); 
  

  
};

You are not using contentSize in your loop like it seems you would want to given its presence. You also insert a copy of value each time through the loop if value does not match when you should only be doing the push_back a single time after reaching the conclusion that the vector does not contain the given value. It seems you could use a call to your contains function to see if the string exists and then do a push_back if it does not.

If you've already figured out the contains function then...

Code:

void StringSet::insert(string value) 
{
    if( !contains(value) )
    {
        // Now it's your turn... what would you put here?
    }
}

I am curious as to why you call it "string set" when it's not a std::set.

In fact, a std::set would have this sort of behavior naturally, although:

1. A std::set is always sorted, you can't specify the order in which the values should be stored (except insofar as you can make sorting rules).

2. A std::set does not have random access iterators, meaning you can't easily access, say, the 25th element in the set. You can easily go through the set in order, and you can easily insert or check to see if a value exists in the set, but you can't easily access based on the position of the element in the set.

Originally Posted by peter_hii

hi cat....first of all, that is just a name which i used to insert vector of string...

from ur reply, u mean use sorting method to sort ? i dont really understand about ur reply... cheers/\.

A std::set will sort all the entries based on operator<, so if you create your own class, you make your own operator< and you can then do whatever you want.

I still don't understand what you think you want to do, but what you should do is call contains inside the insert function, and if it returns true then "fail", otherwise ok. That would mean that the second insert would fail. In that case you want to check in the contains function if count is greater than or equal to 1 (you could also just return immediately if you find a match to avoid looping through the rest of the words).

Then in your insert function, if contains returns true then you don't insert. That way you never have more than one copy of the same string in the vector. You don't want to check the contains function after you insert, because at that point there is already a duplicate.