Question

*****C++ program***** Please implement the following, comments throughout code to explain, and provide screenshots of output for proof.

Write a program for sorting a list of integers in ascending order using the bubble sort algorithm. Implement the following functions:

1. Implement a function called readData
   int readData( int *arr)
   arr is a pointer for storing the integers. The function returns the number of integers.
   The function readData reads the list of integers from a file call data.txt into the array arr. The first integer number in the file is the number of intergers. After the first number, the file lists the integers line by line.
2. void bsort(int *arr, int last)
   arr is a pointer to an array of integers to be sorted. last is the number of elements in the array. The function bsort sorts the list of integers in ascending order.
   Here is the Link to the Bubble Sort.
3. writeToConsole(int * arr, int last)
   arr is a pointer to an array of integers. last is the number of elements in the array. The function writeToConsole displays the sorted list.
4. Do not use the array notation in your solution.

Here is the content of the file data.txt.
9
8
4
7
2
9
5
6
1
3

Answer 1

#include<iostream>
#include<fstream>
#include<sstream>
#include<cstdlib>
using namespace std;
//function that reads the number of integers and those integers
//from data.txt and stores in arr passed to it.
//there is a mistake in passing *arr , it only modifies the arr variable
//in function once the function is executed no modifications are done to arr variable
//that's why double pointer is used and in main function address of arr variable of type int * is passed.
//see the main code for readData function call.
int readData(int **arr)
{
   int len = 0;
   //open file
   ifstream inp("data.txt");
   string line;
   int num = 0;
   //get first line from data.txt
   getline(inp,line);
   //pass it to stringstream object
   stringstream s(line);
   //copy the integer type value in stringstream to num
   s >> num;
   //if num is 0, or instead of number sum text is there in data.txt
   //stringsream assigns nothing and 0 will be still there in num var
   //at that time prompt the user and exit.
   if(num == 0)
   {
       cout<<"\nWarning: Number of Integers specified as 0 or not a number in data.txt.\n";
       cout<<"Not reading file\n";
       inp.close();
       return 0;
   }
   //create memory for array of size num(which is first line value in data.txt)
   *arr = new int[num];
   //till file is read completly
   while(getline(inp,line))
   {
       stringstream ss(line);
       //here stringsream is used it will automatically
       //assigns the read string value into passed datatype variable
       //here num variable of type int is passed. so stringstream will convert
       //the string into integer.
       //if it founds other than integer that is stored in it then
       //it will assigns nothing.that's why for every wrong num in file
       //0 is inserted to achieve this after completion of while block statements
       //each time num is set to 0.
      
       ss >> num;
      
       //assign read num into len_th position of array .
       //since arr var is double pointer use * to get the value in it(base address of type int *arr passed).
       *((*arr)+len) = num;
       //increment length
       len++;
       //increment position
       //num is set to 0 , to achieve invalid number in file are set to 0.
       num = 0;
   }
   inp.close();
   //return the length
   return len;
}
//function that prints the array contents
void writeToConsole(int *arr,int last)
{
   cout<<"\n------- Array Elements --------\n\n";
   //from start element to last element print the array elements
   for(int i =0;i<last;i++)
   {
       cout<<*(arr+i);
       if(i<last -1)
       {
           cout<< " , ";
       }
   }
   cout<<"\n";
}
//function that sorts the array in ascending order
void bsort(int *arr,int last)
{
   int i,j,temp;
   //i -> 0 to last
   for(i = 0;i<last;i++)
   {
       //-> j = 0 to last - j - 1
       for(j = 0;j<last-i-1;j++)
       {
           //swap arr[j] with arr[j+1] if arr[j] is greater than arr[j+1]
           //below is the pointer notation for accessing array values at position j.
           if(*(arr + j) > *(arr+j+1))
           {
               temp = *(arr + j);
               *(arr+j) = *(arr+j+1);
               *(arr+j+1) = temp;
           }
       }
   }
}
int main()
{
   //intially set arr to null
   int *arr = NULL;
   //call readData() by passing arr address because we want to
   //assign memory and insert data.
   int len = readData(&arr);
   //if number of integers read are 0 then exit.
   if(len == 0)
   {
       cout<<"Due to error . No Integers are read in array. Qutting...";
       exit(1);
   }
   cout<<"\n------ Before Sort -----\n";
   //if not print the integers before sort
   writeToConsole(arr,len);
  
   //call bsort() to sort the array
   bsort(arr,len);
  
   cout<<"\n------ After Sort -----\n";
   //finally print the sorted arry to console.
   writeToConsole(arr,len);
   return 0;
}

/*
* ----- data.txt -------
10
9
23
2
24
12
10
5
7
6
7
*/
/*
* ----------- OUTPUT -----------
*
------ Before Sort -----

------- Array Elements --------

9 , 23 , 2 , 24 , 12 , 10 , 5 , 7 , 6 , 7

------ After Sort -----

------- Array Elements --------

2 , 5 , 6 , 7 , 7 , 9 , 10 , 12 , 23 , 24

------------------
(program exited with code: 0)

Press any key to continue . . .
*/