Bài 12

var s,a:string;

begin

write('Nhap xau 1: ');readln(s);

write('Nhap xau 2: ');readln(a);

writeln('Do dai xau 1: ',length(s));

writeln('Do dai xau 2: ',length(a));

readln

end.

Bài 13

var s:string;

i:integer;

begin

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

for i:=1 to length(s) do if s[i]='A' then s[i]:='@';

writeln(s);

readln

end.

Bài 12:

program do_dai;

uses crt;

var s1,s2:string;

begin

       clrscr;

       write('Nhap xau thu nhat: ');  readln(s1);

       write('Nhap xau thu hai: ');  readln(s2);

       writeln('=> Do dai xau thu nhat la: ',length(s1));

       write('  Do dai xau thu hai la: ',length(s2));

       readln;

end.

Bài 13:

program thay_the;
uses crt;
var s:string;
begin
        clrscr;
        write('Nhap xau: ');  readln(s);
        while pos('A',s)<>0 do
                begin
                        insert('@',s,pos('A',s));
                        delete(s,pos('A',s),1);
                end;
        write('Xau sau khi thay the la: ',s);
        readln;
end.