.NET Core C# Requires Chilkat v11.7.0+

Search a PDF with a Regular Expression

See more PDF Text Extraction Examples

Demonstrates searching a PDF with a regular expression (regex: true), limiting the number of results (maxResults), and matching whole words only (wholeWord). .NET Core C#

bool success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The PDF used in this example is available at order_records.pdf

Chilkat.Pdf pdf = new Chilkat.Pdf();
success = pdf.LoadFile("qa_data/pdf/order_records.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Chilkat.JsonObject json = new Chilkat.JsonObject();
Chilkat.JsonObject jsonOut = new Chilkat.JsonObject();

//  Find every order number.  With regex set to true, the query is a regular expression.
json.UpdateString("query","ORD-[0-9]{4}-[0-9]{4}");
json.UpdateBool("regex",true);
//  We only want the matched text, so no context is needed.
json.UpdateInt("context",0);

success = pdf.ExtractText("search",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("Order numbers found: " + Convert.ToString(jsonOut.IntOf("count")));
int i = 0;
int count_i = jsonOut.SizeOfArray("matches");
while (i < count_i) {
    jsonOut.I = i;
    Debug.WriteLine(jsonOut.StringOf("matches[i].text"));
    i = i + 1;
}

//  Find the e-mail addresses, but stop after the first three.
json.UpdateString("query","[a-z0-9._]+@[a-z]+[.][a-z]+");
json.UpdateInt("maxResults",3);
success = pdf.ExtractText("search",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("First three e-mail addresses:");
i = 0;
count_i = jsonOut.SizeOfArray("matches");
while (i < count_i) {
    jsonOut.I = i;
    Debug.WriteLine(jsonOut.StringOf("matches[i].text"));
    i = i + 1;
}

//  wholeWord: true matches only whole words.  The word "cat" appears once in the PDF,
//  but it is also inside "catalog" and "category".
json.Delete("maxResults");
json.UpdateBool("regex",false);
json.UpdateString("query","cat");
success = pdf.ExtractText("search",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("Occurrences of cat (any): " + Convert.ToString(jsonOut.IntOf("count")));

json.UpdateBool("wholeWord",true);
success = pdf.ExtractText("search",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("Occurrences of cat (whole word): " + Convert.ToString(jsonOut.IntOf("count")));

//  Sample output:

//  Order numbers found: 9
//  ORD-2026-0301
//  ORD-2026-0302
//  ORD-2026-0303
//  ORD-2026-0304
//  ORD-2026-0305
//  ORD-2026-0306
//  ORD-2026-0307
//  ORD-2026-0308
//  ORD-2026-0307
//  First three e-mail addresses:
//  alice.moore@example.com
//  bkumar@example.org
//  carla@example.net
//  Occurrences of cat (any): 3
//  Occurrences of cat (whole word): 1