c# - Find occurrences of each value of a datagridview column in a text and display each occurrence to the next column -

i having problem here. trying display how many times each 1 of strings in datagridview column "values" appear. trying display each occurrence next each value(for example want this: 71->4, 83 ->7 , 0b->6 etc.). here code. i'm taking result first one. in advance.

    private void button4_click(object sender, eventargs e)     {         string text = richtextbox1.text;          string[] words = text.split(' ');         foreach (string word in words)         {             datagridview1.rows.add(word);         }          string searchterm = " " ;         foreach (datagridviewrow r in datagridview1.rows )         {             if (searchterm == null || searchterm == string.empty || searchterm.trim().length == 0)             {                 searchterm = r.cells["value_detected"].value.tostring();                  var matchquery = wor in words                                  wor.toupperinvariant() == searchterm.toupperinvariant()                                  select wor;                   int wordcount = matchquery.count();                  r.cells["occur"].value = wordcount.tostring();             }           }             button4.enabled = false;     } 

instead of

if (searchterm == null || searchterm == string.empty || searchterm.trim().length == 0) 

it should :

if (r.cells["value_detected"].value != null)