read int per line c++ error needs solution - c++

Question

hey guys I need help for my read code seems not working properly here's the code. The problem is as shown in the picture, the compiler are supposed to display all 1 million int value but it seems that my write or the display code was wrong. It shows nothing like it's not even reading.
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
#include <vector>
#include <omp.h>
#include <ctime>
#include <cstdlib>
using namespace std;
int* CreateArray( int*);
void shellSortParallel( int*, int);
void shellSortSequential(int*, int);
void InsertSort( int*, int, int, int);
int main()
{
int array_size = 1000000;
int n=0;
int* arr=new int[array_size];
ifstream fin("OUTPUT1.txt");
if(! fin)
{
cout << "File could not be opened." << endl;
}
else
{
cout << "File Opened successfully!!!. Reading data from file into array" << endl;
int data;
while(fin>>data)
{
arr[n] = data;
n++;
}
cout << "Displaying Array..." << endl << endl;
for(int i = 0; i < array_size; i++)
{
cout << arr[i];
}
}
fin.close();
int length = 1000000;
double endTime = 0, startTime = 0, totalTime = 0;
double start, end;
cout << "Program is now sorting using shell sort" <<endl;
startTime = time(NULL);
start = omp_get_wtime();// Start performance timer 1 run
shellSortParallel(arr, length);//Run the algorithm
end = omp_get_wtime();// End performance timer 1 run
endTime = time(NULL);
totalTime = endTime - startTime;
cout << "This is the time it took to run. " << totalTime << endl;// time in seconds
int stupid = 0;
cin >> stupid;
cout << "Program has completed all tasks!!" << endl;
return 0;
}
void shellSortParallel(int array[], int length)
{
int h;
int j = 0;
int temp = 0;
int i = 0;
for(h =length/2; h > 0; h = h/2)
{
#pragma omp parallel for shared( array, length, h, i) default(none)
for( i = 0; i < h; i++)
{
//int ID = omp_get_thread_num();
InsertSort(array, i, length, h);
}
}
}
void InsertSort(int arr[], int i, int length, int half)
{
//cout << ID << " ";
int temp = 0;
int j = 0;
for (int f = half + i; f < length; f = f + half)
{
j = f;
while(j > i && arr[j-half] > arr[j])
{
temp = arr[j];
arr[j] = arr[j-half];
arr[j-half] = temp;
j = j -half;
}
}
}
and here is the short version of the file that I'm going to read. Its a random number between 1 to 1million per line
2377763
88764877846
281327
60
625
86
646127818
14551
2177645
32033
1826761
555173
3415445377
32430
1101
any help would be much appreciate, thank you before

Answer 1

By if(fin>>data) you are not just testing, but retrieving data from stream. I suggest use ifs.good() for testing. Overall, you can write such a code instead
std::ifstream fin ("OUTPUT1.txt", std::ifstream::in);
char c = fin.get();
while (fin.good())
{
std::cout << c;
c = fin.get();
}

Answer 2

arr[n-1] = '\0'; is not correct because it's not an array of character so don't mind.
to correct it:
int data;
while(fin>>data)
{
arr[n] = data;
n++;
}
cout << "Displaying Array..." << endl << endl;
for(int i = 0; i < array_size; i++)
{
cout << arr[i];
}
why allocating such huge array of integers? use vector is a good thing:
vector<int> vec;
ifstream fin("OUTPUT1.txt");
int data;
while(fin >> data)
{
vec.push_back(data);
}
cout << "Displaying Array..." << endl << endl;
for(int i = 0; i < vec.size(); i++)
cout << vec[i] << endl;
fin.close();
88764877846 out band of an integer which causes the loop stop reading so you have to either get values as strings then convert into __int64 or __int128
to read values as strings:
string sLine;
int nLines = 0;
ifstream fin("OUTPUT1.txt");
// first read to get number of lines
while(getline(fin, sLine))
nLines++;
//create an array of strings
string* pstrValues = new string[nLines];
// set the get pointer to the beginning of file because the previous read moved it
fin.clear();
fin.seekg(0, ios::beg);
int i = 0;
while(getline(fin, sLine))
{
pstrValues[i] = sLine;
i++;
}
cout << "Displaying Array..." << endl << endl;
for( i = 0; i < nLines; i++)
cout << pstrValues[i] << endl;
fin.close();
now you have an array of strings convert it to int values but you must convert to __int64 because as I said there are values bigger than size of int (4bytes)