printing array

I'm trying to print the name and number of votes of an entry if it exists. But, i can't figure out how to only print the entries that exist.

Here is my code:

Code:

---

struct candidate
{
        string firstName;
        int votes;
        candidate *next;       
};
int main(int argc, char* argv[])
{
        ifstream inFile ( argv[1] );

        if ( !inFile.is_open() )
        {
                cout << "Could not open file." << endl;
        }
        else
        {
                candidate *array1[12];
                char name[20];
                string currentEntry;                       
               
                //Read names in from file. Hash them into table, or increase votes if entry is already in the table.
                while(!inFile.eof())
                {
                        int flag = 0;
                        int hashSpot;

                        inFile.getline(name, 20);
                        hashSpot = Hash(name,12);
                        currentEntry = name;                       

                                               
                        //If entry is not found, hash it into table.
                        if(flag == 0)
                        {                                       
                                array1[Hash(name,12)] = new candidate;
                                array1[Hash(name,12)]->firstName = name;
                                array1[Hash(name,12)]->votes = 1;
                                array1[Hash(name,12)]->next = NULL;                                       
                        }
                        else
                        {
                                       
                        }
                                               
                }               
               
                //Print names               
                for(int i = 0; i < 12 ; i++)
                {                       
                        cout << endl;
                        cout << 3 << ": ";
                        if(array1[i]->votes != NULL)
                        {
                                cout << array1[3]->firstName << " Votes: " << array1[3]->votes;
                        }
                        cout << endl;                       
                }               
        }
       

        cin.get();
        return 0;
}

---

The problem is that if statement. I need it to only print an entry if there is an entry there, but i can't figure out what to put in that if statement.
I guess i'm a little confused with the array of pointers, and what the values of the array positions are before any entries. If i insert an entry, is the array pointing to that entry, or is it actually the entry.



Any help would be appreciated.

PS: This is suppose to be a hash table using chaining. Also, i can individually print the entries that i know were hashed, so they seem to be being created and hashed successfully.

do not use inFile.eof() to control a loop - read fAQ

votes is integer, so probably simple

if(array1[i]->votes >0)
but you should be sure that votes is initialized to 0 at creation

"if(array1[i]->votes >0)"

I tired that, but the program still crashes.

"but you should be sure that votes is initialized to 0 at creation"

Do you mean initialize it right after the array is created. Like:

Code:

---

candidate *array1[12];
for(int i = 0; i < 12; i++)
{
        array1[i]->votes = 0;
}

---

This is how i tried initializing it.
Isn't the array suppose to be empty (pointing to null) until i put an entry in there? Then, instead of pointing to null, it would point to an entry. So, how could i set votes to 0 if the entry hasn't been created yet? Maybe i'm initializing it incorrectly or something.

Thanks

PS: This is the example i am trying to follow: http://www.sparknotes.com/cs/searchi.../section1.html

this

Code:

---

candidate *array1[12];

---

array is not empty - it is just not initialized
this

Code:

---

candidate *array1[12] = {0};

---

should initialize all members to NULL

so you could check

Code:

---

if(array[i])
{       
  //do something

---

why you do not use std::vector instead?

Code:

---

>                                array1[Hash(name,12)] = new candidate;
>                                array1[Hash(name,12)]->firstName = name;
>                                array1[Hash(name,12)]->votes = 1;
>                                array1[Hash(name,12)]->next = NULL;

---

Why not use hashSpot?

Code:

---

                                array1[hashSpot] = new candidate;
                                array1[hashSpot]->firstName = name;
                                array1[hashSpot]->votes = 1;
                                array1[hashSpot]->next = NULL;

---

>The problem is that if statement. I need it to only print an entry if there is an entry there
You could initialize the array of pointers as null pointers (using either NULL or 0}:

Code:

---

                candidate *array1[12] = {NULL};

---

Then the if() statement would be:

Code:

---

                        if(array1[i] != NULL)

---

Ahh, so i was initializing it wrong.
Thanks guys.

"why you do not use std::vector instead?"
I haven't learned that yet, but i'll look into it and see if i can figure out how it works.

"Why not use hashSpot?"
Thank you for pointing that out. I didn't even notice.

and you may want to look at std::list as well

>Ahh, so i was initializing it wrong.
If you initialize the first element, the rest are default initialized (in this case to the null pointer). In this case, it's equivalent to:

Code:

---

                candidate *array1[12] = {NULL, NULL, NULL, NULL, NULL, NULL,
                NULL, NULL, NULL, NULL, NULL, NULL};

---

For an int array, they would default to 0 after the first element. For a double array, they would default to 0.0.