Find Text in RadPdfViewer

Updated on Jun 24, 2026

Use RadPdfViewer to search the text content of a loaded PDF document. This article explains when to use Find, FindAll, and FindPrevious, how to configure TextSearchOptions, and how to work with the returned SearchResult values.

If you want to let users search through the built-in viewer UI, see Find Dialog.

Find Programmatically

To search programmatically:

1. Load a document in RadPdfViewer.
2. Choose the search method that matches your scenario.
3. Optionally create a TextSearchOptions instance.
4. Check the returned SearchResult value or enumerate all matches.

The programmatic API exposes three main methods:

• Find(string text) and Find(string text, TextSearchOptions options) find the next match.
• FindPrevious(string text) and FindPrevious(string text, TextSearchOptions options) find the previous match.
• FindAll(string text) and FindAll(string text, TextSearchOptions options) return all matches in the current document.

Choose the Right Search Method

Use the search method that matches the navigation behavior you need:

• Use Find to move forward to the next match.
• Use FindPrevious to move backward through existing matches.
• Use FindAll when you need the full set of results, for example to build your own results list or count all occurrences.

Find the Next Match

Use Find when you want the next occurrence of a string, optionally with custom search options.

Example 1: Find the next match with custom options

csharp

string sampleText = "sample text";
TextSearchOptions textSearchOptions =
    new TextSearchOptions(caseSensitive: false, useRegularExpression: false, wholeWordsOnly: true);

SearchResult searchResult = this.pdfViewer.Find(sampleText, textSearchOptions);

vbnet

Dim sampleText As String = "sample text"
Dim textSearchOptions As TextSearchOptions =
    New TextSearchOptions(caseSensitive:=False, useRegularExpression:=False, wholeWordsOnly:=True)

Dim searchResult As SearchResult = Me.pdfViewer.Find(sampleText, textSearchOptions)

Find All Matches

Use FindAll when you need every match in the current document instead of only the next or previous one.

Example 2: Find all matches with custom options

csharp

string sampleText = "sample text";
TextSearchOptions textSearchOptions =
    new TextSearchOptions(caseSensitive: false, useRegularExpression: false, wholeWordsOnly: true);

IEnumerable<SearchResult> searchResults = this.pdfViewer.FindAll(sampleText, textSearchOptions);

vbnet

Dim sampleText As String = "sample text"
Dim textSearchOptions As TextSearchOptions =
    New TextSearchOptions(caseSensitive:=False, useRegularExpression:=False, wholeWordsOnly:=True)

Dim searchResults As IEnumerable(Of SearchResult) = Me.pdfViewer.FindAll(sampleText, textSearchOptions)

Find the Previous Match

Use FindPrevious when the current user flow needs to go back to an earlier occurrence.

Example 3: Find the previous match with custom options

csharp

string sampleText = "sample text";
TextSearchOptions textSearchOptions =
    new TextSearchOptions(caseSensitive: false, useRegularExpression: false, wholeWordsOnly: true);

SearchResult searchResult = this.pdfViewer.FindPrevious(sampleText, textSearchOptions);

vbnet

Dim sampleText As String = "sample text"
Dim textSearchOptions As TextSearchOptions =
    New TextSearchOptions(caseSensitive:=False, useRegularExpression:=False, wholeWordsOnly:=True)

Dim searchResult As SearchResult = Me.pdfViewer.FindPrevious(sampleText, textSearchOptions)

SearchResult

The SearchResult class describes a single search hit. After calling Find or FindPrevious, compare the returned value with SearchResult.NotFound before accessing its properties.

Use these members most often:

• NotFound returns the default result when no match exists.
• Range returns a TextRange that describes where the match starts and ends.
• Result returns the matched text.
• ToString() returns a string representation of the current result.

Example 4: Check whether a match was found

csharp

SearchResult searchResult = this.pdfViewer.Find("sample text");

if (searchResult != SearchResult.NotFound)
{
    TextRange searchResultRange = searchResult.Range;
    string searchResultAsText = searchResult.Result;
}

vbnet

Dim searchResult As SearchResult = Me.pdfViewer.Find("sample text")

If searchResult <> SearchResult.NotFound Then
    Dim searchResultRange As TextRange = searchResult.Range
    Dim searchResultAsText As String = searchResult.Result
End If

Configure TextSearchOptions

Use TextSearchOptions to control how the search engine interprets the input text.

The class provides the following constructors:

• TextSearchOptions(bool caseSensitive)
• TextSearchOptions(bool caseSensitive, bool useRegularExpression)
• TextSearchOptions(bool caseSensitive, bool useRegularExpression, bool wholeWordsOnly)

Use the options as follows:

• Set CaseSensitive to true when letter casing must match exactly.
• Set UseRegularExpression to true when the search text is a regular expression pattern.
• Set WholeWordsOnly to true when partial-word matches must be excluded.

The class also exposes the static Default property, which returns the default search configuration.

Example 5: Create the default search options explicitly

csharp

TextSearchOptions textSearchOptions =
    new TextSearchOptions(caseSensitive: false, useRegularExpression: false, wholeWordsOnly: false);

vbnet

Dim textSearchOptions As TextSearchOptions =
    New TextSearchOptions(caseSensitive:=False, useRegularExpression:=False, wholeWordsOnly:=False)

Example 6: Use the default search options

csharp

TextSearchOptions textSearchOptions = TextSearchOptions.Default;

vbnet

Dim textSearchOptions As TextSearchOptions = TextSearchOptions.Default

The main instance properties are:

• UseRegularExpression: Gets or sets whether the search uses a regular expression.
• CaseSensitive: Gets or sets whether the search respects letter casing.
• WholeWordsOnly: Gets or sets whether only whole-word matches are returned.

The class also exposes the PropertyChanged event, which occurs when a property value changes.

Common Search Workflow

The following example shows a typical search flow:

1. Define the search text.
2. Create search options.
3. Call Find.
4. Check whether a result was found.

Example 7: Run a complete search flow

csharp

string sampleText = "invoice";
TextSearchOptions options = new TextSearchOptions(false, false, true);
SearchResult result = this.pdfViewer.Find(sampleText, options);

if (result == SearchResult.NotFound)
{
    return;
}

string matchedText = result.Result;
TextRange matchedRange = result.Range;

vbnet

Dim sampleText As String = "invoice"
Dim options As New TextSearchOptions(False, False, True)
Dim result As SearchResult = Me.pdfViewer.Find(sampleText, options)

If result = SearchResult.NotFound Then
    Return
End If

Dim matchedText As String = result.Result
Dim matchedRange As TextRange = result.Range

See Also

• Find Dialog