Linked list: Array problem

[CQ75]

The point of this program is to take information from a text file (consisting of several sets of data, each set including a word not bigger than 30 characters and an integer)

I kept getting the error

cpp(134) : error C2440: '=' : cannot convert from 'char []' to 'char [30]'

I tried to fix this by making a typedef of my array, but it didn't seem to help. I don't know why it's not working, shouldn't typedef bind "tempname" to an array of 30 characters and thus eliminate any possible conversion?

#include <iostream>
#include <fstream>
#include <cstddef>

using namespace std;

struct node;

typedef node* link;

struct node
{
	char name[30];
	long ID;
	link next;
};

typedef char element[30];

class list
{
private:
	link head; // I think link referrs to the head in the prompt
	int listsize;
public:
	list();
	//void facepalm
	void fileopen(ifstream & sourcefile, char fname[20]); //fname[20] because it's a new array, otherwise it can be of variable size.
	bool readfile(ifstream & sourcefile, char fname[], long &ID); // gets a name and checks to see if it's the end of the file
	void headbuild(element, long & ID);
	link nodebuild(element, long & ID);
	void headnext(link);
	void printlist();
	void sortlist();
};


	list set;
	

int main()
{
	ifstream sourcefile;


	set.fileopen(sourcefile, "a9.txt");

	cout << "File I/O testing on" << endl;

	element tempname;
	long tempID;

	if(!(set.readfile(sourcefile, tempname, tempID)))
	{
		cout << "list is empty" << endl;
		return 0;
	}

	set.headbuild(tempname, tempID);


	if(!(set.readfile(sourcefile, tempname, tempID)))
	{
		cout << "one item present" << endl;
		return 0;
	}
	
	link tempnext = set.nodebuild(tempname, tempID);

	set.headnext(tempnext);

	link currnode = tempnext;

	while(set.readfile(sourcefile, tempname, tempID))
	{
		tempnext = set.nodebuild(tempname, tempID);
		currnode -> next = tempnext;

		currnode = tempnext;
	}
	

	//list::printlist();
	//link::sortlist();

	return 0;
}

list::list()
{
	list::head = NULL;
	listsize = 0;
}

void list::fileopen(ifstream &sourcefile, char fname[20])
{
	sourcefile.open(fname);
	if (!sourcefile)
	{
		cout << "File does not exist" << endl;
		return;
	}
}

bool list::readfile(ifstream &sourcefile, element tempname, long &tempID)
{
	char reader;
	int count = 0;

	sourcefile.get(reader);

	if (!sourcefile)
	{
		return false;
	}

	while(reader != ' ')
	{
		cout << reader;
		tempname[count] = reader;
		sourcefile.get(reader);
	}

	sourcefile >> tempID;
	cout << ' ' << tempID;
	cout << endl;

	return true;
}

void list::headbuild(element tempname, long &tempID)
{
	set.head = new node;
	set.head -> name = tempname;
	set.head -> ID = tempID;
	set.listsize++;
	return;
}

link list::nodebuild(element tempname, long &tempID)
{
	link templink = new node;
	templink -> name = tempname;
	templink -> ID = tempID;
	set.listsize++;
	return templink;
}

void list::headnext(link tempnext)
{
	set.head -> next = tempnext;

}

[Disch]

1) You cannot assign arrays. You can only assign individual variables/objects. Arrays are multiple variables/objects.

2) Screw char arrays anyway. This is C++, use std::string. Replace all your char arrays with strings and your problems will disappear and you'll have no risk of buffer overflows.

3) If you must stick with char arrays, you can copy strings with the strcpy() function:

char dest[30];
char src[] = "wooo";

// copy 'src' to 'dest'
//dest = src;  // doesn't work
strcpy(dest,src);  // works 

[CQ75]

Thanks! That worked

I didn't want to use char arrays. Every program in this class requires the usage of char arrays instead of strings (what is this, 1996?).


I don't like how they told me to form the link list, either... it's kind of backwards.

If it were me, I'd make the link to the node, THEN build the node, then make another new node and repeat. It makes no sense to make the node then link it backwards to the last node.