quicksort string array help c++

Question

This is my code. I don't know how to get the code to run. Im having problems with quicksorting for string.

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <time.h>
#include <string>
#include <ctime>
#include <stdio.h>



using namespace std;

int count;
template <class T>
void printArray(T ar[], int sz);
template <class T>
void bubbleSort(T ar[], int sz);
void quickSortMain(string items[], int ct);
void quickSort(string items[], int left, int right);

//////////////////////////////////////////////////////////////////////////
// Main Function Implementation
//////////////////////////////////////////////////////////////////////////

int main() {
    int numOfData = 50000;
    string line, temp;
    ofstream resultFile;
    ofstream tableFile;
    double data[100][2];
    string patient[numOfData];
    ifstream dataFile("shufflePatient.txt");
    int i;
    int SIZE = 0;

    cout << "Program to shuffle data" << endl << endl;
    cout << "This program will calculate swapping processes and running time.";


    /*Storing data*/
    cout << "Reading data in process.." << endl;
    if (dataFile.is_open()) {
        i=-1;
        while (dataFile.good()) {
            getline (dataFile, line);
            if (i>=0) patient[i] = line;
            i++;
        }
        dataFile.close();
    }

    SIZE = 5;
    quickSortMain(patient, 5);


    /*Writing to file*/
    cout << "Writing to file.." << endl;
    resultFile.open ("test.txt");
    for (int i=0 ; i<numOfData ; i++) {
        resultFile << patient[i] << "\n";
    }
    resultFile.close();
    system("pause");
    return 0;
}


void quickSortMain(string items[], int ct)
{
  quickSort(items, 0, ct-1);
}


void quickSort(string items[], int left, int right)
{
  int i, j;
  char *x;
  string temp[10];

  i = left;
  j = right;
  x = items[(left+right)/2];

  do {
    while((strcmp(items[i],x) < 0) && (i < right)) {
       i++;
    }
    while((strcmp(items[j],x) > 0) && (j > left)) {
        j--;
    }
    if(i <= j) {
      strcpy(temp, items[i]);
      strcpy(items[i], items[j]);
      strcpy(items[j], temp);
      i++;
      j--;
   }
  } while(i <= j);

  if(left < j) {
     quickSort(items, left, j);
  }
  if(i < right) {
     quickSort(items, i, right);
  }
}









//----------------------------------------------------------------------------
// prints array of size size
//----------------------------------------------------------------------------
template <class T>
void printArray(T patient[], int size)
{
  for(int i = 0; i < size; i++)
    cout << patient[i] << " ";
  cout << endl;
}




//----------------------------------------------------------------------------
// sorts array of size size by Bubble Sort method
//----------------------------------------------------------------------------
template <class T>
void bubbleSort(T patient[], int size) //returning an int
{
    bool noChange = true;
    for(int i = size; i > 0; i--)
  {
    noChange = true;
    for(int j = 1; j < i; j++)
    {
      if(patient[j] < patient[j - 1])
      {
        swap(patient[j], patient[j-1]);
        count = count + 1;
        noChange = false;
      }
    }
    if (noChange)
      return ;
  }
}

The error i got was in this line:

 x = items[(left+right)/2];

I changed

char x*; to string x;

I don't know if that was correct. Now the error im getting is that strcmp and strcpy are not declared. Any help on what i should do next?

Strings can be compared with < and > and assigned with =. No need for strcmp and strcpy. — Retired Ninja
– Retired Ninja, Commented Nov 7, 2013 at 5:12
1. Get rid of the left and right, You only need len if you're remotely proficient with pointer math. 2. Stop using C runtime functions for things provided for your by the C++ runtime, such as the operator < overload for std::string — WhozCraig
– WhozCraig, Commented Nov 7, 2013 at 5:27

john · Accepted Answer · 2013-11-07 05:12:39Z

2

That's correct, now change

strcmp(items[i],x) < 0

to

items[i] < x

and

strcmp(items[j],x) > 0

to

items[j] > x

and

strcpy(temp, items[i]);

to

temp = items[i];

etc.

But really this is a case of RTFM. If you're competent enough to write a quicksort routine you should be competent enough to look up how std::string works. Being able to access reference information is a very important skill for a programmer.

answered Nov 7, 2013 at 5:12

john

88.3k5 gold badges61 silver badges95 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Retired Ninja Over a year ago

Also change string temp[10]; to string temp; although std::swap would be a better choice to swap items.

john Over a year ago

@RetiredNinja Right I missed that. I guess it used to be char temp[10];. std::swap is a better choice but I left it as is to show the equivalence of strcpy and =. Maybe the OP can practice his research skills by looking up std::swap.

user2959974 Over a year ago

thank you for all the comments!! last question. could you guys guide we as to where i should research std::string and std::swap from? most of the websites i open dont really explain both of these that much in regard with quicksort.

john Over a year ago

@user2959974 This one's OK en.cppreference.com/w. Look up std::string and std::swap, but look them up for themselves, not just for quicksort.

WhozCraig Over a year ago

@user2959974 Note: that website is the website for all things related to the C++ language and standard library. It is heads and tails better than anything else you will find online.

Collectives™ on Stack Overflow

quicksort string array help c++

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related