C# Requires Chilkat v11.7.0+

Get Every Occurrence of a Label in a PDF

See more PDF Text Extraction Examples

Demonstrates the "labelOccurrence" option. When the same label appears more than once (for example "Total:" on each of several receipts), "first" (the default) uses the first occurrence, "all" returns every occurrence with its page, and a number selects one occurrence. 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 (three receipts, one per page) is available at three_receipts.pdf

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

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

//  Each of the three pages is a receipt with a "Total:" line.
json.UpdateString("label","Total");
json.UpdateString("labelValue","right");

//  By default only the first occurrence (in reading order) is used.
success = pdf.ExtractText("text",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("First total: " + jsonOut.StringOf("text"));

//  labelOccurrence "all" returns every occurrence.  The "text" member holds the values joined
//  by line breaks, and labelMatches has one entry per occurrence with its page.
json.UpdateString("labelOccurrence","all");
success = pdf.ExtractText("text",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

int i = 0;
int count_i = jsonOut.SizeOfArray("labelMatches");
while (i < count_i) {
    jsonOut.I = i;
    Debug.WriteLine("Page " + Convert.ToString(jsonOut.IntOf("labelMatches[i].page")) + " total: " + jsonOut.StringOf("labelMatches[i].text"));
    i = i + 1;
}

//  A number selects one occurrence: 2 is the second.
json.UpdateInt("labelOccurrence",2);
success = pdf.ExtractText("text",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("Second total: " + jsonOut.StringOf("text"));

//  The occurrences are counted over the selected pages, so combining "pages" with the label
//  is another way to pick one receipt:
json.UpdateString("labelOccurrence","first");
json.UpdateString("pages","3");
json.UpdateString("label","Receipt No.");
success = pdf.ExtractText("text",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("Receipt number on page 3: " + jsonOut.StringOf("text"));

//  Sample output:

//  First total: $19.86
//  Page 1 total: $19.86
//  Page 2 total: $17.34
//  Page 3 total: $23.62
//  Second total: $17.34
//  Receipt number on page 3: 1003