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])

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.

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

Câu 1: 

uses crt;

var st:string;

d,i,dem:integer;

begin

clrscr;

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

d:=length(st);

write('Xau sau khi xoa so la: ');

for i:=1 to d do 

  if not(st[i] in ['0'..'9']) then write(st[i]);

writeln;

dem:=0;

for i:=1 to d do 

  if st[i]=#32 then inc(dem);

writeln('Xau co ',dem,' dau cach');

writeln('Do dai cua xau la: ',d);

readln;

end. 

Câu 2: 

uses crt;

const fi='kq.out'

var st1,st2:string;

f1:text;

begin

clrscr;

write('Nhap xau thu 1:'); readln(st1);

write('Nhap xau thu 2:'); readln(st2);

assign(f1,fi); rewrite(f1);

if length(st2)>length(st1) then writeln(f1,st2)

else writeln(f1,st1);

close(f1);

end.

Câu 3: 

uses crt;

var a:array[1..100]of integer;

i,n,t,dem:integer;

begin

clrscr;

write('Nhap n='); readln(n);

for i:=1 to n do 

  begin

write('A[',i,']='); readln(a[i]);

end;

t:=0;

dem:=0;

for i:=1 to n do 

  if a[i] mod 2=0 then

begin

t:=t+a[i];

inc(dem);

end;

writeln('Trung binh cong cac so chan la: ',t/dem:4:2);

readln;

end.

Program Xau;

Uses crt;

Var St: String;

    i: longint;

Begin

        Clrscr;

        Write('Nhap xau: '); Readln(St);

        For i:=1 to length(St) do

                St[i] := Upcase(St[i]);

        Write('St = ',St);

        Readln

End.

uses crt;

var a,b:string;

i,d:integer;

begin

clrscr;

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

d:=length(a);

b:=''

for i:=1 to d do 

  if a[i] in ['A'..'Z'] then b:=b+a[i];

writeln(b);

readln;

end.

Program HOC24;

var i,d: byte;

s: string;

begin

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

d:=0;

for i:=1 to length(s) do

if s[i]='b' then d:=d+1;

writeln('Co ',d,' ki tu b');

write('Xau moi sau khi da xoa la: ');

for i:=1 to length(s) do if s[i]<>'b' then write(s[i]);

readln

end.