How to do prime reading through a 2D array in asp pages - arrays

Question

For my school project I am supposed to read values from HTML form which has 30 rows and 4 columns.
I've made a 2d array and made the reading like this (please ignore the validation parts):
Sub primeRead()
For i = 0 To 29
cDetails(i, 0) = Request.Form("UnitCode_" & rowID+1)
If cDetails(i,0) = " " Then
response.write("Hello")
Exit For
End If
cDetails(i, 1) = Request.Form("CP_" & rowID)
If cDetails(i, 1) = "15" Or "20" Then
'response.write("Credits points must be 15 or 20")
'Exit For
End If
cDetails(i, 2) = Request.Form("YS_" & rowID)
If cDetails(i, 2) = " " Then
response.write("Hello")
Exit For
End If
cDetails(i, 3) = Request.Form("UM_" & rowID)
If cDetails(i,3) = " " Then
response.write("Hello")
Exit For
End If
rowID = rowID + 1
i = i + 1
Next
End Sub
However, when I output the input taken from the form like this:
<%For x = 0 To 29%>
<tr>
<td> <%response.write(cDetails(x, 0))%><td/>
<td> <%response.write(cDetails(x, 1))%><td/>
<td> <%response.write(cDetails(x, 2))%><td/>
<td> <%response.write(cDetails(x, 3))%><td/>
<td> <%response.write(cDetails(x, 3))%><td/>
<tr/>
<%Next%>
it only shows up to 15 rows. Is there any limitations with 2D arrays VBScript or something else causing this undesirable output?

Answer 1

You're misunderstanding how For loops work. The loop variable is automatically. Incrementing the variable in the loop body on top of that like you do will cause the code to skip every second row. Remove the line i = i + 1 from the loop:
For i = 0 To 29
...
i = i + 1
Next
Also, the condition cDetails(i, 1) = "15" Or "20" will not work the way you seem to expect. It will check if the value cDetails(i, 1) equals "15" or if the string "20" is true. If you want to compare a variable with more than one value you must compare the variable with each value individually:
If cDetails(i, 1) = "15" Or cDetails(i, 1) = "20" Then
...
End If