Thread: Print Array in reverse order

Hey Guys

I am trying to read into 10 integers then print them out
in reverse order using a simple one-dimensional array.
The below code compiles and does work but I am getting a garbage value before the output.

So say I entered 1 - 10 my ouput is: 125214 10 9 8 7 6 5 4 3 2 1

I am wondering why the program is generating this value
as I am not overstepping the bounds of the array. Any help appreciaited.

Code:

#include <iostream>

// main - begins program execution /////////////////////////////////////////////
//
int main(int argc, char *argv[])
{
   const int ARRAY_SIZE = 10;

   int data[ ARRAY_SIZE ];

   std::cout << "Enter ten integers: ";

   for ( int i = 0; i < ARRAY_SIZE; i++ )
   {
      std::cin >> data[ i ];
   }

   std::cout << "\nIn reverse order they are:\n\n";

   for ( int i = ARRAY_SIZE; i >= 0; i-- )
   {
      std::cout << data[ i ] << " ";
   }

   std::cin.get(); // freeze console output window
   std::cin.ignore();

   return 0; // return value from main to OS
}

Where does this for-loop start

Code:

   for ( int i = ARRAY_SIZE; i >= 0; i-- )

and how does this relate to the output of:
125214 10 9 8 7 6 5 4 3 2 1

--
Mats

I think i considered ARRAY_SIZE to be the starting value of 10. Maybe that is my error.

as I am not overstepping the bounds of the array.

But you are!

I think your mistake is just that your forgot that in the typical forward iteration:

Code:

   for ( int i = 0; i < ARRAY_SIZE; i++ )
   {
      std::cout << data[ i ] << " ";
   }

The array index i is never used to index data since the loop exits the moment i = ARRAY_SIZE. However, in your reverse iteration, i indexes data on the first iteration, thus overstepping the bounds of the array.

Managed to solve it. Thanks for your help guys

Code:

for ( int i = ARRAY_SIZE - 1; i >= 0; i-- )

I forgot the -1 after ARRAY_SIZE thus preventing the array over-runing

Originally Posted by swgh

Managed to solve it. Thanks for your help guys

Code:

for ( int i = ARRAY_SIZE - 1; i >= 0; i-- )

I forgot the -1 after ARRAY_SIZE thus preventing the array over-runing

Yes, a simple mistake that I think almost ALL of us has done at one point or another.

--
Mats