Add up data in a column

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For my column Total i want to add up the numbers in my column. So say there are 10 people and only 8 inputed data...then it would be 8/10 * 100..... then i want to divide the number >=14 by the number inputed which would be 8 people

Dim ccount22 = 0
        Dim ccount55 = 0
        For Each b As DataRow In myTable.Rows
            If b.Item("TI (Y/N)").ToString.ToUpper = "Y" Then ccount22 += 1
            If b.Item("TI (Y/N)").ToString.ToUpper = "N" Then ccount55 += 0
        Next
        Me.txtTI.Text = Math.Round((ccount22 / (count)) * 100, 2).ToString() & "%"

Posted 29-Aug-13 5:14am

PythonProgrammer

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Sergey Alexandrovich Kryukov 29-Aug-13 11:19am

Column of what?
—SA

1 solution

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OriginalGriff · Accepted Answer · 2013-08-29T05:35:00

Solution 1

The problem is two fold: First, you don't appear to set a value of count so there is no guarantee that it is anything like what you want - I would suggest that you should set it to myTable.Rows.Count, or set it to zero and increment it in the loop.

More importantly, you are doing integer arithmetic! So if ccount22 is 8, and count is 10, then

VB

count22 / count

Will be

8 / 10

which in integer arithmetic is zero.
There are two things you can do here - swap to explicit float or double, or ahcnge the calculation to make it work with integers:

VB

Me.txtTI.Text = ((ccount22 * 100) / count00).ToString() & "%"

Because you do the multiply first, you end up with

800 / 10

Which is 80, and correct.

BTW: You do realize that your second line within the loop does absolutely nothing useful, don't you? :laugh:

VB

If b.Item("TI (Y/N)").ToString.ToUpper = "N" Then ccount55 += 0

Try:

VB

If b.Item("TI (Y/N)").ToString.ToUpper = "N" Then ccount55 += 1

Instead...

BTW2: That isn't a "nice" way to do it anyway; this is easier to read and a lot more efficient:

VB

For Each b As DataRow In myTable.Rows
    Dim YesNo as string = b.Item("TI (Y/N)").ToString.ToUpper
    If YesNo = "Y" Then ccount22 += 1
    If YesNo = "N" Then ccount55 += 0
Next

Posted 29-Aug-13 5:35am

OriginalGriff

Comments

PythonProgrammer 29-Aug-13 11:50am

woops i gave u my wrong code above here it is..

Dim ccount3 = 0
Dim ccount4 = 0
'For Each c As DataRow In myTable.Rows
If c.Item("Total").ToString.ToUpper >= "14" Then ccount3 += 1
If c.Item("Total").ToString.ToUpper <= "13" Then ccount4 += 1
Next
Me.txtMR.Text = Math.Round((ccount3 / (ccount4)) * 100, 2).ToString() & "%"

OriginalGriff 29-Aug-13 12:01pm

Same problem, same solution - and it isn't a good idea to compare strings for greater-than or less-than. The comparison is a string comparison, which means it doesn't work the way you think it does, because it is evaluated on a character-by-character basis, rather than as a numeric value. That means that the order does not ascend as you would expect:
1
10
11
12
13
14
15
16
17
18
19
2
20
21
22
...

Nelek 29-Aug-13 13:09pm

Tell me. I have to deal with such crap every day. Thats the "Symbol" sorting of the software I use to programm GUIs

OriginalGriff 29-Aug-13 14:04pm

:doh:

Defenestration for the originator may seem cruel, but it's a good solution in the long run!

PythonProgrammer 29-Aug-13 12:03pm

how to i change the ToString then?

OriginalGriff 29-Aug-13 14:00pm

Don't change ToString - just don't use it.
What type is c.Item("Total") at the moment? (Remember, I can't see anything you don't tell me, so I can't "work it out" for myself)
How did you declare the Item array / property?

PythonProgrammer 29-Aug-13 14:05pm

maybe i worded this question wrong..what im trying to do is divde my number by the number of rows that have input..so say there are 17 rows and 10 rows input and only 2 rows are greater than 14 than it would be 2/10 * 100 = 20%

OriginalGriff 29-Aug-13 14:54pm

Yes. But the problem is that integer math doesn't work like that.
When you divide two integers, you get an integer result - which means that any digits to the right of the "decimal point" is discarded, because there is nowhere to store it (in fact, it isn't calculated at all!)

So if you divide any number by a bigger number you always get exactly zero, because there is no info less than one stored.

When you put together a more complex expression, all the intermediate stages are also integer and have no decimal information.
(2 / 10) * 100
Is worked out as
(0) * 100
Or zero!
If you reorder it:
(2 * 100) / 10
Then that evaluates as
(200) / 10
Or twenty, which is what you wanted.

Floats, doubles, and decimals don't work like that: they store fractional info so it works.

This is one of the reasons I prefer C# - the declaration of variables is explicit rather than optional, so you know what you are getting.

PythonProgrammer 29-Aug-13 15:02pm

how would i do what your saying to this...
Dim ccount3 = 0
Dim ccount4 = 0
'For Each c As DataRow In myTable.Rows
If c.Item("Total").ToString.ToUpper >= "14" Then ccount3 += 1
If c.Item("Total").ToString.ToUpper <= "13" Then ccount4 += 1
Next
Me.txtMR.Text = Math.Round((ccount3 / (ccount4)) * 100, 2).ToString() & "%"

OriginalGriff 30-Aug-13 4:28am

As I asked yesterday:
What type is c.Item("Total")?
See above!

PythonProgrammer 30-Aug-13 7:08am

myTable.Columns.Add("Total", GetType(Integer))

OriginalGriff 30-Aug-13 7:33am

So it's an integer? Then compare it with an integer, not a string!
If CInt(c.Item("Total")) >= 14 Then ...

PythonProgrammer 30-Aug-13 7:41am

i tried that already but that does not work

OriginalGriff 30-Aug-13 7:53am

"does not work" is not a helpful error report!
What does it do that you didn't expect, or not do that you did?