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Trying to create a 2D array

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Join Date: Jan 2008

Posts: 77

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number87

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Trying to create a 2D array

Feb 11th, 2008

im trying to create a 2D array using a random generator but the compiler keeps giving me compiling error no matter how i modify the calling function

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <ctime>
 
using namespace std;
 
const int MAX = 4;
 
void constructArray (int a [][MAX], int);
 
 
int main()
{
	int a [MAX];
 
	srand (time (NULL));
 
	constructArray (a [][MAX], MAX);
 
 
 
}
 
void constructArray (int a [][], int size)
{
	for (int i = 0; i < size; i++)
		a [i][size] = rand () % 10;
}
#include <iostream>
#include <ctime>

using namespace std;

const int MAX = 4;

void constructArray (int a [][MAX], int);


int main()
{
	int a [MAX];
	
	srand (time (NULL));
	
	constructArray (a [][MAX], MAX);

	
	
}

void constructArray (int a [][], int size)
{
	for (int i = 0; i < size; i++)
		a [i][size] = rand () % 10;
}

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Join Date: Jan 2008

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Passmark

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Re: Trying to create a 2D array

Feb 11th, 2008

As it is only 3 lines of code do you need a function?

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
const int MAXROW = 4;
const int MAXCOL = 10;
 
int main()
{
  int a [MAXROW][MAXCOL];
  for (int row = 0; row < MAXROW; row++)
    for (int col = 0; col < MAXCOL; col++)
      a[row][col] = rand () % 10;
}
const int MAXROW = 4;
const int MAXCOL = 10;

int main()
{
  int a [MAXROW][MAXCOL];
  for (int row = 0; row < MAXROW; row++)
    for (int col = 0; col < MAXCOL; col++)
      a[row][col] = rand () % 10;
}

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WaltP

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Re: Trying to create a 2D array

Feb 11th, 2008

And array cannot contain 2 empty dimensions in a function. You must fill in at least the left dimension.

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Join Date: Jan 2008

Posts: 77

Reputation: number87 is an unknown quantity at this point

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number87

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Junior Poster in Training

Re: Trying to create a 2D array

Feb 11th, 2008

oh i used a function coz the array would be part of a larger program....

so...if i wanna print the array on screen now...i added in a few more lines....but the compiler gives me an error msg at line 21....
whats wrong there? i filled up both dimensions of the array, why cant it work?

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(Toggle Plain Text)

#include <iostream>
using namespace std;

const int MAXROW = 4;
const int MAXCOL = 10;



int main()
{
  srand(time(NULL));
  
  int a [MAXROW][MAXCOL];
  
  for (int row = 0; row < MAXROW; row++)
  {  
    for (int col = 0; col < MAXCOL; col++)
      {
             a[row][col] = rand () % 10;
      }
  cout << a[row][col] << "\t";
  cout << endl;
  }    
  

}

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niek_e

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Cenosillicaphobiac

Re: Trying to create a 2D array

Feb 11th, 2008

•

Originally Posted by number87

gives me an error msg at line 21....

You've declared 'col' inside the inner for loop. That means that when the loop is done, col is outside of scope.
To solve this problem you would have declare 'int col' in the same scope as where you use it. So right after this line : int a [MAXROW][MAXCOL]; for example. Just put a int col = 0; after it, and remove the 'int' delcaration from the for loop
:

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <iostream>
#include <time.h>
using namespace std;
 
const int MAXROW = 4;
const int MAXCOL = 10;
 
 
 
int main()
{
	srand(time(NULL));
 
	int a [MAXROW][MAXCOL];
	int col=0 ,row =0;
 
	for (row = 0; row < MAXROW; row++)
	{ 
		for (col = 0; col < MAXCOL; col++)
		{
			a[row][col] = rand () % 10;
		}
		cout << a[row][col] << "\t";
		cout << endl;
	} 
 
        return 0;
}
#include <iostream>
#include <time.h>
using namespace std;

const int MAXROW = 4;
const int MAXCOL = 10;



int main()
{
	srand(time(NULL));

	int a [MAXROW][MAXCOL];
	int col=0 ,row =0;

	for (row = 0; row < MAXROW; row++)
	{ 
		for (col = 0; col < MAXCOL; col++)
		{
			a[row][col] = rand () % 10;
		}
		cout << a[row][col] << "\t";
		cout << endl;
	} 

        return 0;
}