c# - How To Select The First line or (first 20 Characters) of a pragraph using Microsoft Office Interop word.? -

i have been trying following code first line or first 20 characters of paragraph using microsoft office interop word 12

microsoft.office.interop.word.application w = new  microsoft.office.interop.word.application();     microsoft.office.interop.word.document doc;     int iparastart = para.range.start;     para.range.text = "a big paragraph comes here …….";     para = doc.paragraphs.add();     int iparaend = para.range.end;    // select first sentance code tried          doc.range(irangestart,irangeend).sentences.first.select(); doc.range(irangestart,irangeend).sentences.first.shading.backgroundpatterncolor=wdcolor.wdcolororange;  // characters code tried  doc.range(irangestart,irangestart+20).select(); 

it seems not working how can . need select either first sentence or first 20 characters

try using (i assumed have open application , word document):

// paragraph range paragraphs = doc.paragraphs; word.paragraph paragraph = paragraphs.first; word.range paragraphrange = paragraph.range; 

selecting first sentence:

word.sentences sentences = paragraphrange.sentences; word.range firstsentence = sentences.first; firstsentence.select(); 

selecting first 20 characters:

if (paragraphrange.text.length > 20) {     word.range range = paragraph.range.duplicate;     range.setrange(range.start, range.start + 20);     range.select(); }