error!! please help!!

[Stephaniei492]

bool Trie::addDictionary (string filename){
        fstream file("sae-sorted.dic", ios::in);
        string word;
        if(!file.is_open())
        
        {
                cout << "File not found!\n";
                return false;
        }        
        while (file >> word) 
        {
               *this += word;
        }
        return true;
}

error: no match for "operator+=" in "*(Trie*)this += word"

Someone please help!!

[Lachlan Easton]

You haven't defined operator+= (with a string rhs) for class Trie.

[Stephaniei492]

I'm not understanding your answer. So, how to fix this?

[FSchwartz]

What do you expect to happen at line 12?

What is the declaration of the class Trie?

[pogrady]

I'm not understanding your answer. So, how to fix this?

Trie& Trie::operator += (std::string& word)
{
    myWord += word;
    return *this;
};

where myWord is a std::string object located within your class.

[Stephaniei492]

Well, I'm sorry but that didn't work. I'm trying to read words from a .txt letter by letter, using overload operator.

[pogrady]

I'm not sure why you would want to overload the operator here anyway. Just add it to your string member. So, instead of this:

while (file >> word) 
        {
               *this += word;
        }

it would be something like this:

while (file >> word) 
        {
               myString += word;  //myString is a std::string object
        }

The std::string library has an operator that will take this syntax.

[Stephaniei492]

Still doesn't work.

This is what I add to class:

 string myWord;
     
     Trie& Trie::operator += (std::string& word)
    {
    myWord += word;
    return *this;
    } 

And this is my function:

 bool Trie::addDictionary (string filename){
        fstream file("sae-sorted.dic", ios::in);
        string word;
        string myString;
        if(!file.is_open())
        
        {
                cout << "File not found!\n";
                return false;
        }        
        while (file >> word) 
        {
               myString += word;
        }
        return true;
} 

I get the error: error: extra qualification "Trie::" on member "operator+="
Please help!! =)

[ne555]

You are defining the member function inside the class, you shouldn't tell the class which it belongs to. (remove the `Trie::' part)

By the way, ¿do you know what a trie is?
Your attempt is quite disappointing.

To insert a word in a trie

void Trie::add_word( std::string word ){
   if( word.empty() ) //we are done inserting
      this->terminator = true; //we mark `end of word'

   subtrie[ word[0] ].add_word( word.substr(1) );
}

//structure
class Trie{
   bool terminator;
   map<char, Trie> subtrie;
};

`subtrie[ word[0] ]' would follow the branch that corresponds to the first letter (create it if it does not exists

[Stephaniei492]

This is the way I was instructed to do it, using this function and overload operator. I'm not trying to insert a word; I'm trying to read the words.


main.cpp:(.text._ZN4TrieC2Ev[_ZN4TrieC5Ev]+0x13): undefined reference to `vtable for Trie'
/tmp/ccQ979Q4.o: In function `Trie::~Trie()':
main.cpp:(.text._ZN4TrieD2Ev[_ZN4TrieD5Ev]+0x13): undefined reference to `vtable for Trie'
collect2: ld returned 1 exit status

What does this error even mean?

[ne555]

> I'm not trying to insert a word; I'm trying to read the words.

std::string word;
while( cin>>word )
   ; //do nothing