Thread: Help With Merging Sorted Lists of Strings

I am presently working on taking two lists of strings, sorting them, and then merging them into one list of strings that is already sorted without sorting the third list. So far this is the code that I have:

Code:

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

void qsort(int, int, string[]);

int main()
{
	int i = 0, j = 0, k = 0;
	string list1[15], list2[10], list3[25];
	
	cout << "\nThis program will take 2 unsorted lists and merge them into one sorted list.";
	
	for (i = 0; i < 15; i++)
	{
		cout << "\nEnter value for the number " << (i + 1) << " item of your first list.\n";
		cin >> list1[i];
	}

	qsort (0, 14, list1);
	cout << endl;

	for (j = 0; j < 15; j++)
	{
		cout << list1[j];
		cout << endl;
	}

	i = 0;
	j = 0;

	for (i = 0; i < 10; i++)
	{
		cout << "\nEnter value for the number " << (i + 1) << " item of your second list.\n";
		cin >> list2[i];
	}	
	
	qsort(0, 9, list2);
	cout << endl;

	for (j = 0; j < 10; j++)
	{
		cout << list2[j];
		cout << endl;
	}


	return 0;
}


//Purpose:    Function to quickly sort a group of data.
//Calls:      Recursive.
//Globals:    None.

void qsort(int first, int last, string list[])
{
	int middle, p, index;
	string temp, partition;
	if (first < last)
	{
		middle = int(first + last)/2;
		temp = list[middle];
		list[middle] = list[first];
		list[first] = temp;
		partition = list[first];
		p = first;
		for (index = first + 1; index <= last; index++)
		{
			if(list[index] < partition)
			{
				p = p + 1;
				temp = list[index];
				list[index] = list[p];
				list[p] = temp;
			}
		}	
		temp = list[first];
		list[first] = list[p];
		list[p] = temp;
		qsort(first, p - 1, list);
		qsort(p + 1, last, list);
	}
}

I can input the two lists, and I have them sorted then printed out, but how would I go about merging them without having to sort them again?

Well, I got it all to work now, except for the fact that when one of the arrays runs out of items I get a run-time error because of falling out of bounds of the array. How do I account for that and just add the remainder of the array to the end of the third array?

well first you have to put it in a loop statement, that is true when the arrays arent done yet. so that it will exit when one or both arrays are done. after that you need to check which array is infact done, you can check that in the algorithm itself or after, once you establish which array is done, for the array that is not done, you must copy from the last point used, and place in the third array.