/in/foo.cc: In function 'int main()':
/in/foo.cc:7:8: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    7 |  while(cin.getline(str,400)){
      |        ^~~
      |        std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:75,
                 from /in/foo.cc:1:
/usr/include/c++/9/iostream:60:18: note: 'std::cin' declared here
   60 |   extern istream cin;  /// Linked to standard input
      |                  ^~~
/in/foo.cc:8:16: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
    8 |   for(int i=0;i<strlen(str);i++){
      |               ~^~~~~~~~~~~~
/in/foo.cc:17:17: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   17 |    for(int i=0;i<strlen(str);i++){
      |                ~^~~~~~~~~~~~
/in/foo.cc:18:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   18 |     cout<<str[i];
      |     ^~~~
      |     std::cout
In file included from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:75,
                 from /in/foo.cc:1:
/usr/include/c++/9/iostream:61:18: note: 'std::cout' declared here
   61 |   extern ostream cout;  /// Linked to standard output
      |                  ^~~~
/in/foo.cc:20:4: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 |    cout<<endl;
      |    ^~~~
      |    std::cout
In file included from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:75,
                 from /in/foo.cc:1:
/usr/include/c++/9/iostream:61:18: note: 'std::cout' declared here
   61 |   extern ostream cout;  /// Linked to standard output
      |                  ^~~~
/in/foo.cc:20:10: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   20 |    cout<<endl;
      |          ^~~~
      |          std::endl
In file included from /usr/include/c++/9/istream:39,
                 from /usr/include/c++/9/sstream:38,
                 from /usr/include/c++/9/complex:45,
                 from /usr/include/c++/9/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:54,
                 from /in/foo.cc:1:
/usr/include/c++/9/ostream:599:5: note: 'std::endl' declared here
  599 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
/in/foo.cc:22:8: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   22 |   else cout<<"输入不符合要求"<<endl;
      |        ^~~~
      |        std::cout
In file included from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:75,
                 from /in/foo.cc:1:
/usr/include/c++/9/iostream:61:18: note: 'std::cout' declared here
   61 |   extern ostream cout;  /// Linked to standard output
      |                  ^~~~
/in/foo.cc:22:39: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   22 |   else cout<<"输入不符合要求"<<endl;
      |                                       ^~~~
      |                                       std::endl
In file included from /usr/include/c++/9/istream:39,
                 from /usr/include/c++/9/sstream:38,
                 from /usr/include/c++/9/complex:45,
                 from /usr/include/c++/9/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:54,
                 from /in/foo.cc:1:
/usr/include/c++/9/ostream:599:5: note: 'std::endl' declared here
  599 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
/in/foo.cc:23:1: error: expected '}' at end of input
   23 | }
      | ^
/in/foo.cc:4:1: note: to match this '{'
    4 | {
      | ^