1 #include "../../st.h" 2  3 int main() 4 try{ 5     string s1="a.txt"; 6     string s2="z.txt"; 7     ifstream ifs(s1.c_str()); 8     if(!ifs) 9         error("can not open input file",s1);10     ofstream ofs(s2.c_str());11     if(!ofs)12         error("can not open output file1",s2);13     char ch;14     while(ifs.get(ch))15     {16         if(isalpha(ch))17             ch=tolower(ch);18         ofs<<ch;19     }20     keep_window_open();21 }22 catch(exception&e){23     cerr<<e.what()<<endl;24     while(1);25     return 1;26 }27 28 catch(...){29     cerr<<"exception\n";30     while(1);31     return 2;32 }33     

 1 int fn() 2 { 3     char c; 4     cin>>c; 5     if(c==‘0‘) 6     { 7         char c1; 8         cin>>c1; 9         if(c1==‘x‘)10         {11             cin.putback(c1);12             cin.putback(c);13             return 16;14         }15         else16         {17             cin.putback(c1);18             cin.putback(c);19             return 8;20         }21     }22     else23     {24         cin.putback(c);25         return 10;26 27     }28 29 }30 31 int main()32 {33     int i;34     cin.unsetf(ios::hex);35     cin.unsetf(ios::dec);36     cin.unsetf(ios::oct);37     cout<<showbase;38     int p=fn();39     cin>>i;40     switch (p)41     {42     case 16:43         cout<<hex<<i<<"  hexadecimal  converts to "<<dec<<i<<" decimal"<<endl;44         break;45     case 8:46         cout<<oct<<i<<"  octmal  converts to "<<dec<<i<<" decimal"<<endl;47         break;48     case 10:49         cout<<dec<<i<<" decimal  converts to "<<dec<<i<<" decimal"<<endl;50         break;51     default:52         break;53     }54     while(1);55     return 0;56 57 }