program ChuyenXauSangChuThuong;
var
  str: string; 
  i: integer; 

begin
  write('Nhap mot xau ky tu: ');
  readln(str); 
  for i := 1 to Length(str) do
    str[i] := LowerCase(str[i]); 
  writeln('Xau ky tu chuyen thanh chu thuong la: ', str); 
end.

Var s,st:string;

i:integer;

Begin

Write('Nhap xau ');readln(s);

For i:=1 to length(s) do

If s[i] in ['0'..'9'] then st:=st+s[i];

Write('Cac ki tu so co trong day la ',st);

Readln

End.

giúp em với ạ em cảm ơn nhìuu

Program HOC24;

var i,d1,d2: byte;

st1,st2: string[60];

begin

write('Nhap xau st1: '); readln(st1);

//---------------Câu 1-------------------

d1:=0; d2:=0;

for i:=1 to length(st1) do

begin

if st1[i]='A' then d1:=d1+1;

if st1[i]='a' then d2:=d2+1;

end;

writeln('Co ',d1,' ki tu A trong xau');

writeln('Co ',d2,' ki tu a trong xau');

//---------------------- Câu 2 --------------------

st2:=''

for i:=1 to length(st1) do if st1[i] in ['a'..'z'] then st2:=st2+st1[i];

writeln('Xau st2 la: ',st2);

//------------------------------Câu 3--------------------

for i:=1 to length(st1) do st1[i]:=upcase(st1[i]);

write('Xau st1 sau khi in hoa la: ',st1);

//--------------------------------------------------------

readln

end.

uses crt;

var st:string[50];

d,i:integer;

begin

clrscr;

write('Nhap xau:'); readln(st);

d:=length(st);

for i:=1 to d do 

  if st[i] in ['a'..'z'] then write(st[i]:4);

readln;

end.

uses crt;

var s,s1,s2:string;

i,d:integer;

begin

clrscr;

readln(s);

s1:=''

s2:=''

d:=length(s);

for i:=1 to d do

  begin

if s[i] in ['0'..'9'] then s1:=s1+s[i];

if (s[i] in ['a'..'z']) or (s[i] in ['A'..'Z']) then s2:=s2+s[i];

end;

writeln('Xau chua cac ki tu so la: ',s1);

writeln('Xau chua cac ki tu chu la: ',s2);

readln;

end.

2:

uses crt;

var st:string;

d,i,dem1,dem2:integer;

begin

clrscr;

write('Nhap xau:'); readln(st);

d:=length(st);

dem1:=0;

dem2:=0;

for i:=1 to d do

  begin

if st[i] in ['0'..'9'] then inc(dem1);

if (st[i] in ['a'..'z']) or (st[i] in ['A'..'Z']) then inc(dem2);

end;

writeln('So ki tu la chu so la: ',dem1);

writeln('So ki tu la chu cai la: ',dem2);

for i:=1 to d do 

  if st[i] in ['0'..'9'] then delete(st,i,1);

writeln('Xau sau khi xoa cac chu so la: ',st);

readln;

end. 

program stringManipulation;

var
  st1, st2: string;
  countN, i: integer;

begin
  write('Nhap vao xau ki tu st1: ');
  readln(st1);
  countN := 0;
  for i := 1 to length(st1) do
  begin
    if (st1[i] = 'N') or (st1[i] = 'n') then
    begin
      countN := countN + 1;
    end;
  end;
  writeln('So ky tu N va n trong xau st1 la: ', countN);
  st2 := ''
  for i := 1 to length(st1) do
  begin
    if (st1[i] >= 'A') and (st1[i] <= 'Z') then
    begin
      st2 := st2 + st1[i];
    end;
  end;
  writeln('Cac ky tu in hoa trong xau st1 la: ', st2);
  write('Xau st1 viet theo chieu nguoc lai la: ');
  for i := length(st1) downto 1 do
  begin
    write(st1[i]);
  end;
  readln;
end.

st1 = input("Nhập vào xâu kí tự: ")
count_n = 0
st2 = ""
for char in st1:
    if char == 'N' or char == 'n':
        count_n += 1
    if char.isupper():
        st2 += char

print("Số lần xuất hiện của kí tự 'N' và 'n' là:", count_n)
print("Xâu kí tự chỉ chứa kí tự in hoa là:", st2)
print("Xâu kí tự đảo ngược là:", st1[::-1])

uses crt;

var st:string;

i,d,dem:integer;

begin

clrscr;

write('Nhap xau:'); readln(st);

d:=length(st);

dem:=0;

for i:=1 to d do 

  if (st[i] in ['a'..'z']) or (st[i] in ['A'..'Z']) then inc(dem);

writeln(dem);

readln;

end.