单个字符串反转

int main()
 {
string str;
 cout<<"Please input string:";
 cin>>str;
 string::size_type len=str.size();                                                                                                                           
 for( string::size_type i=0;i!=len/2;i++)
 {
 char temp;
 temp=str[i];
 str[i]=str[len-i-1];
 str[len-i-1]=temp;
 
}
 cout<<str<<endl;

return 0;
}