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Need help with pointer output using array and pointer notation

Posted on 2007-11-14
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Last Modified: 2013-12-14
Ok this is a continuation question.. I am using pointer notation with the output being in a function and the input being in the main body. Problem is it compiles works except the output is not the numbers reversed it is a weird output.

Here is my code:

#include <iostream>

using namespace std;

void arrayRev();

const int SIZE = 5;

int main()
{
      int numbers[SIZE];
      int* p_numbers;
      int counter;
      p_numbers = numbers;

      cout << "Enter five integers: ";

      for (counter = 0; counter < SIZE; counter++)
      {
            cin >> numbers[counter];
            cout << "Enter five integers: ";
      }
     
      cout << endl;

      arrayRev();

      return 0;
}
void arrayRev()
{
      int numbers[SIZE];
      int* p_numbers;
      int counter;
      p_numbers = numbers;

      cout << "The numbers in reverse are: ";

      for (counter = 4; counter >= 0; counter--)
            cout << *(p_numbers+counter) << " ";
      cout << endl;
}
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Question by:jschmuff
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8 Comments
 
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Accepted Solution

by:
Anthony2000 earned 250 total points
ID: 20286301
The main problems that I see is that there are two separate arrays with the same name: numbers - you need to have only one, you could make it global by declaring it after the statement: const int SIZE = 5;
And remove the two declarations (one in main and the one in arrayRev
 
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Expert Comment

by:Anthony2000
ID: 20286307
Do you understand why? This is important to know for future code writing.
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 20286314
Indeed you are not passing the list to the output function, so basically you are printing garbage, it should be something like:

int main()
{
      int numbers[SIZE];
      int* p_numbers;
      int counter;
      p_numbers = numbers;

      cout << "Enter five integers: ";

      for (counter = 0; counter < SIZE; counter++)
      {
            cin >> numbers[counter];
            cout << "Enter five integers: ";
      }
     
      cout << endl;

      arrayRev(numbers);

      return 0;
}
void arrayRev(int *p_numbers)
{
      int counter;

      cout << "The numbers in reverse are: ";

      for (counter = 4; counter >= 0; counter--)
            cout << *(p_numbers+counter) << " ";
      cout << endl;
}
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Author Comment

by:jschmuff
ID: 20286326
That version of the code to try produced an error:

.\main.cpp(26) : error C2660: 'arrayRev' : function does not take 1 arguments
0
 

Author Comment

by:jschmuff
ID: 20286351
ok so I declared int numbers[SIZE]; //before main function

removed it from both arrayRev function and the main.

seems to work properly now. Thanks for the help and I do understand I knew once you said to declare it globally I was beginning to see the real problem with the code. Now that I got that working just curious would there be a way to turn this into a class dont worry this is my assignment I just wanna know if it would be possible just in case your not sure of my homework this is my assignment:

Write a C++ function ReverseArray using "pointer notation" that will write out the elements of an array of int in reverse order.
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 20286353
yeah, you need to change the function prototype too, to match the real function:

#include <iostream>
using namespace std;

void arrayRev(int *);  // <------------this must change too

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LVL 55

Expert Comment

by:Jaime Olivares
ID: 20286358
if you declare the array as global, then you don't need to pass as an argument, but this version is more reusable.
about the class, you can make a "StringReverser" class and put the function just made as a method.
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Expert Comment

by:Infinity08
ID: 20287533
>> ok so I declared int numbers[SIZE]; //before main function

There's no need for that. Passing it as a parameter is a lot better (see also your other thread where this has also been suggested a few times).

If you have trouble with function parameters, then I suggest to check this tutorial :

        http://www.cplusplus.com/doc/tutorial/functions.html
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