Search text

GroupDocs.Parser provides the functionality to search text from documents by the Search(string) and Search(string, SearchOptions) methods:

IEnumerable<SearchResult> Search(string keyword);
IEnumerable<SearchResult> Search(string keyword, SearchOptions options);

The keyword parameter can contain a text or a regular expression. SearchResult class contains every occurrence of the keyword in the document text. This class has the following members:

MemberDescription
PositionA zero-based index of the start position of the search result. Depending on SearchOptions.SearchByPages property value this index starts from the document start or the document page start.
PageIndexThe page index where the text is found.
TextThe found text.
LeftHighlightItemThe left highlight.
RightHighlightItemThe right highlight.

Search text by keyword

Here are the steps to search a keyword in the document:

  • Instantiate Parser object for the initial document;
  • Call Search(string) method and obtain collection of SearchResult objects;
  • Check if collection isn’t null (search is supported for the document);
  • Iterate through the collection and get position and text.

The following example shows how to find a keyword in a document:

// Create an instance of Parser class
using(Parser parser = new Parser(filePath))
{
    // Search a keyword:
    IEnumerable<SearchResult> sr = parser.Search("page number");
    // Check if search is supported
    if(sr == null)
    {
        Console.WriteLine("Search isn't supported");
        return;
    }

    // Iterate over search results
    foreach(SearchResult s in sr)
    {
        // Print an index and found text:
        Console.WriteLine(string.Format("At {0}: {1}", s.Position, s.Text));
    }
}

Search text by regular expression

SearchOptions parameter is used to customize a search. This class has the following members:

MemberDescription
MatchCaseThe value that indicates whether a text case isn’t ignored.
MatchWholeWordThe value that indicates whether text search is limited by the whole word.
SearchByPagesThe value that indicates whether the search is performed by pages.
UseRegularExpressionThe value that indicates whether a regular expression is used.
LeftHighlightOptionsThe options for the left highlight.
RightHighlightOptionsThe options for the right highlight.

Here are the steps to search with a regular expression in the document:

  • Instantiate Parser object for the initial document;
  • Instantiate SearchOptions object with the parameters for the search;
  • Call Search(string, SearchOptions) method and obtain collection of SearchResult objects;
  • Check if collection isn’t null (search is supported for the document);
  • Iterate through the collection and get position and text.

The following example shows how to search with a regular expression in a document:

// Create an instance of Parser class
using(Parser parser = new Parser(filePath))
{
    // Search with a regular expression with case matching
    IEnumerable<SearchResult> sr = parser.Search("page number: [0-9]+", new SearchOptions(true, false, true));
    // Check if search is supported
    if(sr == null)
    {
        Console.WriteLine("Search isn't supported");
        return;
    }

    // Iterate over search results
    foreach(SearchResult s in sr)
    {
        // Print an index and found text:
        Console.WriteLine(string.Format("At {0}: {1}", s.Position, s.Text));
    }
}

Search text with highlights

Here are the steps to search text with a highlights:

  • Instantiate Parser object for the initial document;
  • Instantiate HighlightOptions object with the parameters for the highlight extraction;
  • Instantiate SearchOptions object with the parameters for the search;
  • Call Search(string, SearchOptions) method and obtain collection of SearchResult objects;
  • Check if collection isn’t null (search is supported for the document);
  • Iterate through the collection and get position and text.

The following example shows how to search a text with the highlights:

// Create an instance of Parser class
using (Parser parser = new Parser(Constants.SamplePdf))
{
    HighlightOptions highlightOptions = new HighlightOptions(15);
    // Search a keyword:
    IEnumerable<SearchResult> sr = parser.Search("lorem", new SearchOptions(true, false, false, highlightOptions));
    // Check if search is supported
    if (sr == null)
    {
        Console.WriteLine("Search isn't supported");
        return;
    }
    // Iterate over search results
    foreach (SearchResult s in sr)
    {
        // Print the found text and highlights: 
        Console.WriteLine(string.Format("{0}{1}{2}", s.LeftHighlightItem.Text, s.Text, s.RightHighlightItem.Text));
    }
}

Search text with page numbers

Here are the steps to search text with page numbers:

  • Instantiate Parser object for the initial document;
  • Instantiate SearchOptions object with the parameters for the search;
  • Call Search(string, SearchOptions) method and obtain collection of SearchResult objects;
  • Check if collection isn’t null (search is supported for the document);
  • Iterate through the collection and get position, text and page number.

The following example shows how to search a text with page numbers:

// Create an instance of Parser class
using(Parser parser = new Parser(Constants.SamplePdf))
{
    // Search a keyword with page numbers
    IEnumerable<SearchResult> sr = parser.Search("lorem", new SearchOptions(false, false, false, true));
    // Check if search is supported
    if(sr == null)
    {
        Console.WriteLine("Search isn't supported");
        return;
    }
 
    // Iterate over search results
    foreach(SearchResult s in sr)
    {
        // Print an index, page number and found text:
        Console.WriteLine(string.Format("At {0} (page {1}): {2}", s.Position, s.PageIndex, s.Text));
    }
}

More resources

GitHub examples

You may easily run the code above and see the feature in action in our GitHub examples:

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