Question

So my test.h file has:

#include <iostream>
#include <fstream>

using namespace std;

class test
{
private:
   int data[];

public:
   test(string filename);
};

My test.cpp file has:

#include "sort.h"

test::test(string filename)
{
   ifstream inFile;

   inFile.open(filename);

   int iter = 0;

   while(!inFile.eof())
   {
       cin >> data[iter];
       iter++;
   }

   int numberOfNumbers = iter;

   for (iter = 0; iter < numberOfNumbers; iter++)
       cout << data[iter] << " ";

   inFile.close();
}

my main.cpp has:

#include "sort.h"

int main()
{
   sort numbers("test.txt");
}

the numbers in my test.txt file are

10

20

30

40

50

My question is how do I populate the array in my class with the numbers in the text file and print it using the constructor. When I run my code right now, nothing shows up on the screen.

Answer 1

Firstly, You are including "sort.h" which you haven't defined. Check if that is not causing any problem.

Now I can see this code can't populate your array.
Because you are using cin which is used to take inputs from command line or input buffer.

You can use "filename >> integer" which stores next integer from file into specified integer.

For example, in your code write like this:
int iter=0;
int input_int;
while(inFile >> input_int) {
   data[iter]=input_int;
   iter++;
}

This will work for populating your array.
Here's how I debugged your code using data you spoecified.

//So my test.h file has:

#include <iostream>
#include <fstream>

using namespace std;

class test
{
private:
int data[100];

public:
test(string filename);
};

//My test.cpp file has:

//#include "sort.h"

test::test(string filename)
{
ifstream inFile;

inFile.open(filename);

int iter = 0;
   int input_int;
while(inFile >> input_int)
{
data[iter]=input_int;
iter++;
}

int numberOfNumbers = iter;

for (iter = 0; iter < numberOfNumbers; iter++)
cout << data[iter] << " ";

inFile.close();
}

//my main.cpp has:

//#include "sort.h"

int main()
{
// sort numbers("test.txt");
test("test.txt");
}

Another thing, Don't forget to initialize the size of array as that might cause error.

Hope you got it... :)