Page through an Array Help !

cIdiot · #1 06-Sep-2004, 05:21

How can I page through an Array in C++, say with 10 elements and I want to display only first 3 elements, then when I hit ENTER, the next 3 elements will be displayed and so on till the last element of the Array is reached.

For example:

CPP / C++ / C Code:

int array[10];           
for (j = 1 ; j <= 10 ; j++)
{
   cout << array[j] << endl;
}

Thanks in advance.

LuciWiz · #2 06-Sep-2004, 08:18

Something like this?

CPP / C++ / C Code:

	int a[12];
	int old = 0;

	for (int i = 0; i < 12; i++)
		a[i] = i;

	for (int it = 3; it <= 12; it += 3)
	{
		for(int j = old; j < it; j++)
			cout << a[j] << " ";
		cout << endl;
		getchar();
		old = it;
	}

davekw7x · #3 06-Sep-2004, 09:33

Quote:

Originally Posted by LuciWiz

Something like this?

CPP / C++ / C Code:

	int a[12];
	int old = 0;

	for (int i = 0; i < 12; i++)
		a[i] = i;

	for (int it = 3; it <= 12; it += 3)
	{
		for(int j = old; j < it; j++)
			cout << a[j] << " ";
		cout << endl;
		getchar();
		old = it;
	}

How would you handle the case where there are 10 elements (as suggested in the original post)? Or any case where the number of elements in the array is not an exact multiple of 3?

Think about a single loop: print the values one at a time. Put a space after each value, or format the output any way you want.

The first line has

a[0] a[1] a[2]

Then you want to put out an endl, and let the user press Enter.

so the second line has

a[3] a[4] a[5]

Etc. (You exit the loop when you have printed all of the numbers in the array.)

How do you know when to end a line and let the user press Enter?

Well, consider the modulo operator (%). Did you wonder why they would put something this bizarre in the C language (carried over to C++)?

Well we are doing things three at a time. Here's where you use the modulo operator.

Try the following:

CPP / C++ / C Code:

#include <iostream>

using std::cout;
using std::endl;

int main()
{
  cout << "Simple investigation of the modulo operator:" << endl << endl;
  for (int i = 0; i < 12; i++) {
    cout << i << " % 3 = " << i % 3 << endl;
  }
  return 0;
}

Now in your program you want to end the line when i = 2, i = 5, i = 8, etc.

What is the value of i % 3 when i = 2, i = 5, etc.?

Good Luck and Best Regards,

Dave

cIdiot · #4 06-Sep-2004, 22:31

Thanks guys, that's was quick and well explained

The modulo method was so helpful.

It's much easier than I thought before. Just simply adding an IF statement inside the loop to check the remainder. My final version is:

CPP / C++ / C Code:

const pageSize = 3;
int array[10]; 
char key;          
for (j = 1 ; j <= 10 ; j++)
{
   cout << array[j] << endl;

   if ( j % pageSize == 0 )
   cin >> key;
}

Regards,

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