刚刚学Pascal，请问这段程序怎么写

var
a,b,i:integer;
ch,ch1,ch2:char;
s:string;
begin
readln(s);
write(s[length(s)],'=');
delete(s,length(s)-1,2);
i:=1;
while s[i] in ['0'..'9'] do begin a:=a*10+ord(s[i])-48;inc(i);end;
ch:=s[i];i:=i+1;
while s[i] in ['0'..'9'] do begin b:=b*10+ord(s[i])-48;inc(i);end;
case ch of
'+':write(a+b);
'-':write(a-b);
'*':write(a*b);
'/':write(a/b:0:2);
end;
end.

字符串处理.......

program test

var
a,b:integer;//两个数
c:char;//运算符
begin
readln(a);
readln(c);
readln(b);
case c of
'*':writeln(a*b);
'/':writeln(a/b);
'+':writeln(a+b);
'-'writeln(a-b);
end;
readln;
end.

这程序其实不难，学的多了你就会写了，这是字符串处理的，下面是程序：
var
a,b:integer;//两个数
c:char;//运算符
begin
readln(a);
readln(