Building and coding a program to draw a rectangle of asterisks in visual basic-CodePudding

I am trying to build a for loop that greats a rectangle with asterisks where a user can enter the number of rows and columns they would wish displayed. I am able to get the rows working correctly but I unable to get the columns to work as they should. Could anyone correct me on where am going wrong:

Private Sub cmdProcess_Click(sender As Object, e As EventArgs) Handles cmdProcess.Click
    Dim rows As Integer
    Dim columns As Integer

    rows = txtRow.Text
    columns = txtColumn.Text

    lbloutput.Text = ""
    For i = 1 To rows
        lbloutput.Text = lbloutput.Text & "*" & vbCrLf

    Next

End Sub

CodePudding user response：

Before anything else: your code will error if the user enters a negative number, or 0. Unless you have any other code to address this, you might want to try something like this:

rows = Abs(cInt(txtRow.Text))
columns = Abs(cInt(txtColumn.Text))
if rows*columns < 1 Then Exit Sub

(If your code is in VBA, rather than VB, then there is no advantage to using Integer over Long, as they both use the same amount of memory — an Integer just locks half of it out as unusable)

A naïve approach would be to use two loops, like so:

lbloutput.Text = ""
For i = 1 To rows 'How many lines of text?
    For j = 1 to columns 'How many asterisks per line?
        lbloutput.Text = lbloutput.Text & "*"
    Next j
    lbloutput.Text = lbloutput.Text & vbCrLf
Next i

However, a simpler method would be to use the String function:

lbloutput.Text = ""
For i = 1 To rows
    lbloutput.Text = lbloutput.Text & String(columns, "*") & vbCrLf
Next i