编一个程序,使其输出值为反项的,如输入217,输出为712

用delphi实现很简单

uses StrUtils;

var
str1,str2:string;
begin
str1:='217';
str2:=ReverseString(str1);
edit1.text:=str2;
end;

C语言~~~~~~~~~~~~~~~~~~
#include <stdio.h>
#define N 3 /*输入数字的位数*/
main()
{
int a[N],i;
for(i=0;i<N;i++)
scanf("%1d",&a[i]);
for(i=N-1;i>=0;i--)
printf("%d",a[i]);

}

var three:integer;
begin
read(three);
if three<0 then write('-');
three:=abs(three);
repeat
write(three mod 10);
three:=three div 10;
until three=0;
writeln;
end.

最直接的
var st:string;
i:integer;
begin
readln(st);
for i:=length(st) downto 1 do write(st[i]);
end.

var
s:ansistring;
i:longint;
begin
while not eof do begin
readln(s);
for i:=length(s) downto 1 do wirte(s[i]);
writeln;
end;