1.11

#include<iostream>
#include <string>
using namespace std;
int main()
{
int i,n;
string s1,s2;
cout<<"输入一个字符串：";
cin>>s1;
n=s1.size();
s2=s1;
for(i=0;i<n;i++)
{
s2[i]=s1[n-i-1];
}
cout<<endl<<s2<<endl;
return 0;
}