xau = input("Nhập vào một xâu bất kì: ")

xau_moi = xau.replace("choi", "hoc")

print("Xâu mới sau khi thay thế là:", xau_moi)

Program HOC24;

var s: string;

d: byte;

begin

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

while pos('choi',s)<>0 do

begin

d:=pos('choi',s);

delete(s,d,4);

insert('hoc',s,d);

end;

write('Xau sau khi thay la: ',s);

readln

end.

Bài 1:

uses crt;

var S:String;

vt:integer;

begin

clrscr;

Write(‘Nhap 1 xau:’); Readln(S);

While pos(‘nang’,s)>0 do

Begin

Vt:= pos(‘nang’,s);

Delete(s,vt,4);

Insert(‘mua’,s ,vt);

End;

Writeln(‘Xau sau khi thay the ’,s);

Readln;

End.

Bài 2: 

uses crt;

var st:string;

d,i,kt:integer;

begin

clrscr;

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

d:=length(st);

kt:=0;

for i:=1 to d do 

  if st[i]<>st[d-i+1] then kt:=1;

if kt=0 then writeln(st,' la xau doi xung')

else writeln(st,' khong la xau doi xung');

readln;

end.

Program HOC24;

var s: string;

i: byte;

begin

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

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

readln

end.

uses crt;

var st:string;

i,d:integer;

begin

clrscr;

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

d:=length(st);

for i:=1 to d do 

 if st[i]='a' then delete(st,i,1);

writeln(st);

readln;

end.

uses crt;

var st:string;

n,vt,d,i:integer;

begin

clrscr;

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

d:=length(st);

write('Nhap vi tri can xoa:'); readln(vt);

write('Nhap so ki tu can xoa:'); readln(n);

delete(st,vt,n);

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

readln;

end.

tham khảo

uses crt;

var st:string;

i,d:integer;

begin

clrscr;

readln(st);

d:=length(st);

for i:=1 to d do 

  if (not (st[i] in ['A'..'Z'])) and (not (st[i] in ['a'..'z'])) then write(st[i]);

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] in ['0'..'9'] then d:=d+1;

write('Co ',d,' ki tu so trong xau');

readln

end.

Program HOC24;

var s: string;

begin

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

for i:=1 to length(s) do if s[i]<>#32 then write(s[i]);

readln

end.

uses crt;

var st:string;

a:array[1..255]of string;

i,d,dem,kt,j,dem1:integer;

begin

clrscr;

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

d:=length(st);

a[1]:=st[1];

dem:=1;

for i:=1 to d do 

  begin

kt:=0;

for j:=1 to dem do 

  if st[i]=a[j] then kt:=1;

if kt=0 then 

begin

inc(dem);

a[dem]:=st[i];

end;

end;

for i:=1 to dem do 

  begin

dem1:=0;

for j:=1 to d do 

  if a[i]=st[j] then inc(dem1);

writeln(a[i],' xuat hien ',dem1,' lan');

end;

readln;

end.

uses crt;

var a:string;

     c:char;

     i,dem:integer;

begin

    clrscr;

    readln(a);

    readln(c);

    dem:=0;

    for i:=1 to length(a) do

    if a[i]=c then dem:=dem+1;

    writeln(dem);

    readln;

end.

Bài 3: 

uses crt;

const fi='teptong.txt';

var a,b:integer;

f1:text;

begin

clrscr;

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

readln(a,b);

writeln(a+b);

writeln(f1,a+b);

close(f1);

readln;

end.