Counting the # of items in an array

I have this prog and what I need to do is have the user input their numbers and print the array, Then, for it to count the number of times the number was inputted and print a histogram of the number of times it was used. EX:

2.......10........3.5
4.......3.5 ..........21
3.........8...........7
//etc....

response ........# of times....... Histogram
1 .................... 2 ..................**
2 ................... 1 .......................*
//etc....

Here is what I have and I am unsure of the last few lines. I copied the last couple of lines from another example, I just included it because I know it will look somewhat to those lines. Please help, any help appreciated!

Code:

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

const int numrow = 5;
const int numcol = 3;

int main ()
{
double nums[numrow][numcol];
	
	for (int i = 0; i <numrow; i++)
{
	for (int j = 0; j < numcol; j++)
{
	cout << "enter grades for row # " << (i + 1)<< ": ";
	cin >> nums [i][j];
}
}
	for (int a = 0; a < numrow; a++)
{
                for (int b = 0; b < numcol; b++)
{
               cout << setw (4) << nums [a][b];
}
               cout << "Response" << setw( 13 ) << "Frequency"
                << setw( 17 ) << "Histogram" << endl;

   for ( int i; i < numrow; i++ ) 
{
      cout << setw( 7 ) << i << setw( 13 ) 
           << n[ i ] << setw( 9 );

      for ( int j = 0; j < n[ i ]; j++ )   // print one bar
      cout << '*';
   
   cout << endl;
}
   return 0;
}

Here is what I have and I am unsure of the last few lines. I copied the last couple of lines from another example, I just included it because I know it will look somewhat to those lines.

What do you think those 'last few lines' are supposed to do?

> Please help, any help appreciated!
But always ignored
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