[<<D>>]

Код:

function getindexofletter(letter,fromstring:string):integer;
var i:integer;
begin
result:=0;
for i:=1 to length(fromstring) do
begin
if copy(fromstring,i,1)=letter then
result:=i;
end;
end;

.....
var
s:string;
Numb:integer;
begin
s:='abcdefghijklmnopqrstuvwxyz';
numb:=getindexofletter('a',s);