Question

我试图找出如何搜索我的数组，然后找到我在原始文本框中显示的条目。

        If idTextBox.Text = String.Empty Or nameTextBox.Text = String.Empty Then
        MessageBox.Show("Please enter a valid name and/or ID number.")
    Else
        'retrieve user input & add to array
        studentArray(0, columnId) = idTextBox.Text
        studentArray(1, columnId) = nameTextBox.Text
        studentArray(2, columnId) = majorComboBox.Text
        studentArray(3, columnId) = yearComboBox.Text
        If honorsRadioButton.Checked = True Then
            studentArray(4, columnId) = "1"
        ElseIf notHonorsRadioButton.Checked = True Then
            studentArray(4, columnId) = "0"
        End If

这是我的搜索和显示代码，当我搜索数组中不存在的ID时，它会崩溃。

Dim findstudentid As Integer
Dim didFindIt As Boolean = False
Integer.TryParse(idTextBox.Text, findstudentid)

If findstudentid <> 0 Then
    Dim foundIt As Integer
    Dim highColumn As Integer = studentArray.GetUpperBound(0)

    'search each column of the first row
    For columnID As Integer = 0 To highColumn
        If findstudentid = CDbl(studentArray(0, columnID)) Then
            foundIt = columnID
            didFindIt = True
            Exit For
        End If
    Next

    If didFindIt Then
        'read from array and write to interface
        idTextBox.Text = studentArray(0, foundIt)
        nameTextBox.Text = studentArray(1, foundIt)
    Else
        MessageBox.Show("Student data is not found. Please re-enter or add the student data!", "Student Information", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

        idTextBox.Focus()
    End If
Else
    MessageBox.Show("Please enter a student id.", "Student Information", MessageBoxButtons.OK, MessageBoxIcon.Error)
    idTextBox.Focus()
End If

Answer 1

这是一个OOP方法的例子。使用此函数，您可以在调用它之前检查null / Nothing的返回值属性（会出错）。您甚至可以使用对象或List(Of T)进行DataBinding。

Public Class Student
 Public Property Id As Integer
 Public Property Name As String
 Public Property Major As String
 Public Property Year As Integer
 Public Property Honors As Boolean
End Class

以您的形式：

Public Class FrmMain : Inherits Form
 Private Students As New List(Of Student)

 Private Sub btnNewStudent(sender As Object, e As EventArgs) Handles btnNewStudent.Click
  Dim _student As New Student
  'fill the properties 
  Students.Add(_student)
 End Sub
 '...
End Class
Private Function FindStudent(Id As Integer) As Student
  'return the student by Id or object with by Nothing
  Return Students.Where(Function(s) s.Id = Id).FirstOrDefault
End Function

Answer 2

我想通了

    Dim findstudentid As Integer
    Dim didFindIt As Boolean = False
    Integer.TryParse(idTextBox.Text, findstudentid)

    If findstudentid <> 0 Then
        Dim foundIt As Integer
        Dim highColumn As Integer = studentArray.GetUpperBound(0)

        'search each column of the first row
        For columnID As Integer = 0 To highColumn
            If findstudentid = CDbl(studentArray(0, columnID)) Then
                foundIt = columnID
                didFindIt = True
                Exit For
            End If
        Next

        If didFindIt Then
            'read from array and write to interface
            idTextBox.Text = studentArray(0, foundIt)
            nameTextBox.Text = studentArray(1, foundIt)
        Else
            MessageBox.Show("Student data is not found. Please re-enter or add the student data!", "Student Information", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

            idTextBox.Focus()
        End If
    Else
        MessageBox.Show("Please enter a student id.", "Student Information", MessageBoxButtons.OK, MessageBoxIcon.Error)
        idTextBox.Focus()
    End If

如何在文本框中搜索数组和显示？

2 个答案: