Question

How can i get the index of a datagridview row by column value of that row ? And also , how can i update the datagridview when a value of a column has been changed ?

Answer 1

Re comment — find which rows contain a value of x:

Should be something like this (not tested)

List<int> rowsOfInterest = new List<int>();

foreach(DataGridViewRow row in dgv.Rows)
  if (row.Cells["Column I want"].Value == ValueIWant)
    rowsOfInterest.Add(row.Index);

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I think what you want is this, but your question is not 100% clear.

foreach(object value in dgv.Rows[rowindex].Cells)
   // check is value is one needed