Question

Hi!

1. I need some help with sorting string in a text file. My goal is to 1 shift left strings for string.length time. I was able to do that successfully. However, I am also trying to sort, using insertion sort , the resulting shifts. I store all shifts in a vector (or is it better to use an array?!) , and try to sort them that way, but my output is just the shifted strings but not sorted. Can anybody help with that? Also, let me know where I made a mistake.

2. Lastly, the sorted values should be written to a different file. When I try to do that, an ofstream file is created, but nothing is written to it.

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LeftShift2.txt

Hi there!

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#include <iostream>

#include <string>

#include <vector>

#include <algorithm>

#include <fstream>

using namespace std;

void shiftleft (string& s, int d)

{

reverse(s.begin(), s.begin() + d);

reverse(s.begin() + d, s.end());

reverse(s.begin(), s.end());

}

void insertionSort(vector<string> &arr)

{

int i, j;

string key;

for (i = 1; i < arr.size(); i++)

{

key = arr[i];

j = i - 1;

while (j >= 0 && arr[j] > key)

{

arr[j + 1] = arr[j];

j = j - 1;

}

arr[j + 1] = key;

}

}

void printArray(vector<string> array) {

for (int i = 0; i < array.size()-1; ++i)

cout << array[i] << endl;

}

int main(int argc, char *argv[])

{

string i;

string input_line;

vector<string> value;

cout << "encode" << endl;

getline(cin, i);

ifstream infile("LeftShift2.txt");

ofstream ofile("LeftShift3.txt");

if(infile.is_open() && i == "insertion")

{

while(getline(infile, input_line))

{

for(int i = 0; i < input_line.size(); i++)

{

cout << input_line << endl;

shiftleft (input_line, 1);

}

}

value.push_back(input_line);//push individual input_line into vector value

insertionSort(value);//lexicographically sort values in vector value.

printArray(value);//test to see if all element are sorted

ofile << infile.rdbuf();//copy sorted content of infile in ofile

}

}

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LeftShift3.txt should be something like (notice how sorted lexicographically following ASCII table):

_there!Hi (_here is space)

!Hi there

e!Hi ther

so on and so forth

Answer 1

Solution:

There were 3 problems:

1. inserting the shifted string in vector. You were doing it outside the while loop in main function. You are printing the value inside for loop, so the shifted string should be pushed just after calling the shiftleft function. value.push_back(input_line); statement should be inside for loop.

2. second problem in writing in output file using ofile. Like you have iterated through vector and printing it on screen in printArray function, the vector should be iterated and written elements one by one in file.

3. not closing the infile and ofile. you should call infile and ofile after use.

Program:

#include "stdafx.h"
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <fstream>

using namespace std;

void shiftleft(string& s, int d)
{
   reverse(s.begin(), s.begin() + d);
   reverse(s.begin() + d, s.end());
   reverse(s.begin(), s.end());
}

void insertionSort(vector<string> &arr)
{
   int i, j;
   string key;

   for (i = 1; i < arr.size(); i++)
   {
       key = arr[i];
       j = i - 1;

       while (j >= 0 && arr[j] > key)
       {
           arr[j + 1] = arr[j];
           j = j - 1;
       }

       arr[j + 1] = key;
   }
}

void printArray(vector<string> array) {
   for (int i = 0; i < array.size() - 1; ++i)
       cout << array[i] << endl;
}

int main(int argc, char *argv[])
{
   string i;
   string input_line;
   vector<string> value;

   cout << "encode" << endl;

   getline(cin, i);

   ifstream infile("LeftShift2.txt");
   ofstream ofile("LeftShift3.txt", ofstream::out);

   if (infile.is_open() && i == "insertion")
   {
       while (getline(infile, input_line))
       {
           for (int i = 0; i < input_line.size(); i++)
           {
               cout << input_line << endl;
               shiftleft(input_line, 1);

               value.push_back(input_line);//push individual input_line into vector value
           }
       }

       insertionSort(value);//lexicographically sort values in vector value.

       printArray(value);//test to see if all element are sorted

       //ofile << infile.rdbuf();//copy sorted content of infile in ofile

       ofile << "Hello" << endl;

       for (int i = 0; i < value.size() - 1; ++i)
           ofile << value[i].data() << endl;

       infile.close();
       ofile.close();
   }

   return 0;
}

Output:

encode insertion Hi there! i there!H there!Hi t he re!Hi he reHi t ereHi th re!Hi the e?Hi ther !Hi there the re!Hi Hi there Hi there e?Hi ther ereHi th he re!Hi t i there!H re! Hi the

Output file content:

LeftShift3.txt - Notepad | File Edit Format View Help there! Hi !Hi there Hi there! e! Hi ther ere! Hi th here! Hi t i there!H re! Hi the