Chương trình:
uses crt; {thu vien dung cho viec xoa man hinh}
var Dem:array[‘A’..‘Z’] of integer;
____S: String;
____ch: char;
____i: integer;
begin
____clrscr; {lenh xoa man hinh}
____write[‘Nhap xau S: ’];
____readln[S];
_for ch:= ‘A’ to ‘Z’ do
_______Dem[ch]:= 0;
_ for i:=1 to length[S] do
begin
if S[i] in [[‘a’..‘z’]] then {co the thay bang if [S[i] >= ‘a’] and [S[i]