datagridview column index
// To retrieve a DataGridView column by name you simply reference it through the columns
// collection indexer:
datagridview1.Columns["columnName"]
// Then you can get the column index from that column:
datagridview1.Columns["columnName"].Index;
// Do note that if you use an invalid column name then this reference will return null,
// so you may want to check that the column reference is not null before using it,
// or use the columns collection .Contains() method first.