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.