c = {'Fp1','Fp2','F3','F4','C3','C4','P3'
'P4' ,'O1' ,'O2','F7','F8','T7','T8'};
idx = strcmpi('O1',c);
where idx is a logical array (same dim as c) that is true (1) where 'O1' is found in c.
To get the row and the column with find:
[r,c] = find(idx);
If you need r and c to retrieve O1 or to use them on an array the same dimension as c then I suggest to use idx. It is preferred in terms of performance to use logical indexes and to avoid calling find.
