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Fix incorrect usage of regex in WPF sample #2250

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Fix incorrect usage of regex in WPF sample #2250

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b987c72
Fix regex usage in WPF sample
GrabYourPitchforks Jul 1, 2026
cc15ad3
Fix empty string issue in regex sample
GrabYourPitchforks Jul 2, 2026
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34 changes: 29 additions & 5 deletions ...uide/samples/snippets/csharp/VS_Snippets_Wpf/DialogBoxSample/CSharp/FindDialogBox.xaml.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,19 +50,31 @@ public int Length

void findNextButton_Click(object sender, RoutedEventArgs e)
{
string textToFind = this.findWhatTextBox.Text;

// Short-circuit: Did the user not provide any text at all?
if (string.IsNullOrEmpty(textToFind)) return;

// Find matches
if (this.matches == null)
{
string pattern = this.findWhatTextBox.Text;
RegexOptions regexOptions = RegexOptions.None;

// Escape the user-typed text in case it contains regex special characters.
string pattern = Regex.Escape(textToFind);

// Match whole word?
if ((bool)this.matchWholeWordCheckBox.IsChecked) pattern = @"(?<=\W{0,1})" + pattern + @"(?=\W)";
if ((bool)this.matchWholeWordCheckBox.IsChecked)
{
if (BeginsWithRegexWordChar(textToFind)) pattern = @"\b" + pattern;
if (EndsWithRegexWordChar(textToFind)) pattern = pattern + @"\b";
}

// Case sensitive
if (!(bool)this.caseSensitiveCheckBox.IsChecked) pattern = "(?i)" + pattern;
if (!(bool)this.caseSensitiveCheckBox.IsChecked) regexOptions |= RegexOptions.IgnoreCase;

// Find matches
this.matches = Regex.Matches(this.textBoxToSearch.Text, pattern);
this.matches = Regex.Matches(this.textBoxToSearch.Text, pattern, regexOptions);
this.matchIndex = 0;

// Word not found?
Expand All @@ -77,7 +89,7 @@ void findNextButton_Click(object sender, RoutedEventArgs e)
// Start at beginning of matches if the last find selected the last match
if (this.matchIndex == this.matches.Count)
{
MessageBoxResult result = MessageBox.Show("Nmore matches found. Start at beginning?", "Find", MessageBoxButton.YesNo);
MessageBoxResult result = MessageBox.Show("No more matches found. Start at beginning?", "Find", MessageBoxButton.YesNo);
if (result == MessageBoxResult.No) return;

// Reset
Expand All @@ -96,6 +108,18 @@ void findNextButton_Click(object sender, RoutedEventArgs e)
this.matchIndex++;
}

static bool BeginsWithRegexWordChar(string literal)
{
if (string.IsNullOrEmpty(literal)) return false;
return Regex.IsMatch(literal[0].ToString(), @"\w");
}

static bool EndsWithRegexWordChar(string literal)
{
if (string.IsNullOrEmpty(literal)) return false;
return Regex.IsMatch(literal[literal.Length - 1].ToString(), @"\w");
}

void textBoxToSearch_TextChanged(object sender, TextChangedEventArgs e)
{
ResetFind();
Expand Down
37 changes: 30 additions & 7 deletions ...es/snippets/visualbasic/VS_Snippets_Wpf/DialogBoxSample/VisualBasic/FindDialogBox.xaml.vb
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Original file line number Diff line number Diff line change
Expand Up @@ -33,15 +33,28 @@ Namespace SDKSample
End Sub

Private Sub findNextButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
Dim textToFind As String = Me.findWhatTextBox.Text

' Short-circuit: Did the user not provide any text at all?
If String.IsNullOrEmpty(textToFind) Then Return

If (Me.matches Is Nothing) Then
Dim pattern As String = Me.findWhatTextBox.Text
Dim matchOptions As RegexOptions = RegexOptions.None

' Escape the user-typed text in case it contains regex special characters.
Dim pattern As String = Regex.Escape(textToFind)

' Match whole word?
If Me.matchWholeWordCheckBox.IsChecked.Value Then
pattern = ("(?<=\W{0,1})" & pattern & "(?=\W)")
End If
If Not Me.caseSensitiveCheckBox.IsChecked.Value Then
pattern = ("(?i)" & pattern)
If BeginsWithRegexWordChar(textToFind) Then pattern = "\b" & pattern
If EndsWithRegexWordChar(textToFind) Then pattern = pattern & "\b"
End If
Me.matches = Regex.Matches(Me.textBoxToSearch.Text, pattern)

' Case sensitive
If Not Me.caseSensitiveCheckBox.IsChecked.Value Then matchOptions = matchOptions Or RegexOptions.IgnoreCase

' Find matches
Me.matches = Regex.Matches(Me.textBoxToSearch.Text, pattern, matchOptions)
Me.matchIndex = 0
If (Me.matches.Count = 0) Then
MessageBox.Show(("'" & Me.findWhatTextBox.Text & "' not found."), "Find")
Expand All @@ -50,7 +63,7 @@ Namespace SDKSample
End If
End If
If (Me.matchIndex = Me.matches.Count) Then
Dim result As MessageBoxResult = MessageBox.Show("Nmore matches found. Start at beginning?", "Find", MessageBoxButton.YesNo)
Dim result As MessageBoxResult = MessageBox.Show("No more matches found. Start at beginning?", "Find", MessageBoxButton.YesNo)
If (result = MessageBoxResult.No) Then
Return
End If
Expand All @@ -65,6 +78,16 @@ Namespace SDKSample
Me.matchIndex += 1
End Sub

Private Shared Function BeginsWithRegexWordChar(ByVal literal As String) As Boolean
If String.IsNullOrEmpty(literal) Then Return False
Return Regex.IsMatch(literal(0).ToString(), "\w")
End Function

Private Shared Function EndsWithRegexWordChar(ByVal literal As String) As Boolean
If String.IsNullOrEmpty(literal) Then Return False
Return Regex.IsMatch(literal(literal.Length - 1).ToString(), "\w")
End Function

Private Sub findWhatTextBox_TextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)
Me.ResetFind()
End Sub
Expand Down
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