alphabetize my list c++

AquamaN · 10-21-2005, 01:23 AM

So I've been working my way through my program and i've got a list of strings (list<string> stringList) and it contains a few hundred words. Now I want to put them in alphabetical order. Is the best way to do this just a generic bubble sort? Just comparing the first one to the next, if it's higher swap them out and keep going down the list? Any thoughts would be appreciated. Thanks.

-aquaman

Winno · 10-21-2005, 02:58 AM

You tried using stringList.sort() ? I got from here that you could use that with strings.

As for the bubble sort, it is a very rudimentry type of sort. It might be OK for a short list on a modern CPU, but for long lists and big apps, I'd use more efficient algorithms like quicksort and heapsort. On a small scale, an insertion sort is better than bubble, and you can sort each element as it's being added to the list.

spooon · 10-21-2005, 03:24 AM

Yes you should use C++'s sort algorithm, which uses introsort. Here is the correct way to use it:

Code:

#include <algorithm>

sort( stringList.begin(), stringList.end() );

lowpro2k3 · 10-21-2005, 10:31 AM

Sorting a list is a very slow task btw, even with quicksort. But for a few hundred entries, who cares. I would use a list for large collections that need to be sorted though.

AquamaN · 10-21-2005, 01:57 PM

Quote:

Originally posted by spooon
Yes you should use C++'s sort algorithm, which uses introsort. Here is the correct way to use it:

Code:

#include <algorithm> sort( stringList.begin(), stringList.end() );

Doesn't seem like that wants to work on my list<string> stringList; ... Hmm.. This is what I have so far

Code:

#include <iostream>
#include <fstream>
#include <string>
#include <list>
#include <algorithm>
#include "myList.h"


using namespace std;

int main ()
{
	char line[150], *temp;
	ifstream inputText;
	string words;
	int longestWord = 0, totalWords = 0;
	int wordIndex = 0, y = 0;
	list<string> stringList;
	list<string>::iterator itString;
	list<listIndex> indexList;
	list<listIndex>::iterator itIndex;
	listIndex *tempList;
	word *tempWord;
	
	inputText.open("blah.txt");
	
	while(!inputText.eof())
	{
		inputText.getline(line, 150);
		temp = strtok(line, " 1234567890!;\"./'()?,-");
		while(temp != NULL)
		{
			words = temp;
			//lowercase all words
			for(unsigned int i = 0; i < words.size( ); i++ ) 
				words[i] = tolower(words[i]); 
			
			//get longest word length to ascertain number of indecies
			if(words.size() > longestWord)
				longestWord = words.size();
			
			stringList.push_back(words);
			
			temp = strtok(NULL, " 1234567890!;\"./'()?,-");
		}
	}
	
	//get total number of words in list
	for(itString = stringList.begin(); itString != stringList.end(); itString++)
		totalWords++;
	
       //This is where I want to Sort the stringList...
	sort(stringList.begin(), stringList.end());

and when I compile it with that sort() function in there, this is what I get:

Code:

usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h: In function 'void std::sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]':
main.cpp:52:   instantiated from here
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2570: error: no match for 'operator-' in '__last - __first'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h: In function 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]':
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2571:   instantiated from 'void std::sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]'
main.cpp:52:   instantiated from here
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2214: error: no match for 'operator-' in '__last - __first'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2216: error: no match for 'operator+' in '__first + _S_threshold'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2217: error: no match for 'operator+' in '__first + _S_threshold'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h: In function 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]':
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2220:   instantiated from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2571:   instantiated from 'void std::sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]'
main.cpp:52:   instantiated from here
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2130: error: no match for 'operator+' in '__first + 1'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2220:   instantiated from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]'
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2571:   instantiated from 'void std::sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = std::_List_iterator<std::string>]'
main.cpp:52:   instantiated from here
/usr/include/gcc/darwin/4.0/c++/bits/stl_algo.h:2136: error: no match for 'operator+' in '__i + 1'

any thoughts?

AquamaN · 10-21-2005, 02:12 PM

Ok, proper code is:

Code:

stringList.sort();

thanks all!

lowpro2k3 · 10-21-2005, 02:25 PM

Heres an example you can play with. I recommend a book on the STL, or at least a generic C++ book with an excellent chapter on the subject.

Code:

#include <iostream>
#include <list>
#include <string>
#include <algorithm>
using namespace std;

int main()
{
 list<string> li;

 li.push_back("joe");
 li.push_back("bob");
 li.push_back("amy");
 li.push_back("ned");
 li.push_back("steph");

 li.sort();
 for(list<string>::iterator i = li.begin(); i != li.end(); ++i)
 {
  cout << *i << endl;
 }

 return 0;
}

Outputs:
amy
bob
joe
ned
steph

lowpro2k3 · 10-21-2005, 02:30 PM

Quote:

Originally posted by AquamaN
Ok, proper code is:

Code:

stringList.sort();

thanks all!

Ah I was too late

Theres also a list function:
list::sort(CompFunc op)

For sorting objects for you, you just provide a comparison function although I'm a little rusty on how to use them. I've done similiar stuff in C with the library function qsort() but I haven't written one in C++. Just something to keep in mind for the future, it could prove to be handy.

ta0kira · 10-25-2005, 01:20 AM

Well, if you don't mind treading off the path of the STL, I've got a list class that can sort just as fast as anything. I use it for everything myself. It's memory-safe since the allocation is strictly managed internally by STL containers. It's much easier than messing with iterators, which, in my opinion, can introduce hard to trace bugs. Let me know if you like it if you do decide to try it out. Thanks.
https://sourceforge.net/projects/clist-ta0kira/
ta0kira