Console crashes outputting pointer array and iterations C++

Question

I am busy working on a simple concept to display pointer arrays and iterations of a for loop in C++

My compiler is not giving much away and when I run the program the console is saying the following and returning 3 "The application has requested the Runtime to terminate in an unusual way.

The crash occurs on this line:

      cout << i + 1 << " " << *(pArray + i) << endl;

but when I run this program ommiting either i + 1 or *(pArray + i) it runs without errors or crashing.

Is it illegal to try and output as I am trying to do above?

See below for the code:

#include <iostream>
#include <cstdlib>
using namespace std;

int main() {

int * pArray;
int SIZE;
int module;
pArray = new int[SIZE];  

cout <<"Enter the number of Assignments ";
cin >> SIZE;

cout <<"input assignment number " ;

    for (int i = 0; i < SIZE; i++)    
   {    
        cin >> module;    
        *(pArray + i) = module;

   }
   // Print array
   for (int i = 0; i < SIZE; i++)
   {
  cout << i + 1 << " " << *(pArray + i) << endl;
   }
   cout << endl;

   delete[] pArray;  // Deallocate array via delete[] operator

   return 0;
}

I am admittedly a little nervous to ask this question but I just need someone to explain why this is happening as I am battling to find any reference on this type of situation.

Thanks

It could be an idea to assign some value to SIZE, before using it. — Cheers and hth. - Alf
– Cheers and hth. - Alf, Commented Oct 10, 2015 at 12:38

Alan Stokes · Accepted Answer · 2015-10-10 12:39:01Z

1

You use SIZE two lines before you initialize it.

Move

pArray = new int[SIZE];

to after where you obtain the value of SIZE.

(Also: this would be so much easier with std::vector.)

answered Oct 10, 2015 at 12:39

Alan Stokes

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1 Comment

Metamorphosis Over a year ago

Thank you! I feel intensely dim. I feel despondent each time I ask a question on this forum as I am continuously marked down. I am very new C++ and occasionally as a student studying long distance I feel overwhelmed with these concepts and just appreciate a bit of interaction. Thanks again :)

basav · Accepted Answer · 2015-10-10 12:43:58Z

1

int * pArray;
int SIZE;
int module;
pArray = new int[SIZE];

SIZE is not initialised yet, so, it would be some junk value. Initialise it before using it.

You could also Check for success/failure of new.

pArray = new(nothrow) int[SIZE];

if(pArray)
//logic

answered Oct 10, 2015 at 12:43

basav

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5 Comments

Metamorphosis Over a year ago

Thank you for your input. This makes sense. Not sure how I missed that.

Alan Stokes Over a year ago

It's very unlkely that new would fail here; and if it did the resulting exception would seem to be a perfectly good way to expose that.

Metamorphosis Over a year ago

@AlanStokes So then are you are saying that if I build an exception handler like above it would catch this is size hadn't been initialized?

Alan Stokes Over a year ago

No. I'm saying that @basav's second suggestion wouldn't improve things. If the new fails you will find out about it anyway. (It might fail given uninitialised input, but it might not.)

basav Over a year ago

@Alan: agreed .in normal circumstances, not needed.i come from an embedded background and again, it really depends on the use case

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