/in/foo.cc: In function 'int main()':
/in/foo.cc:7:17: error: too many arguments to function 'int getchar()'
  while(getchar(c)){
                 ^
In file included from /usr/include/stdio.h:935:0,
                 from /usr/include/c++/6/cstdio:42,
                 from /usr/include/c++/6/ext/string_conversions.h:43,
                 from /usr/include/c++/6/bits/basic_string.h:5417,
                 from /usr/include/c++/6/string:52,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/x86_64-linux-gnu/bits/stdio.h:44:1: note: declared here
 getchar (void)
 ^~~~~~~
/in/foo.cc:8:11: warning: comparison with string literal results in unspecified behavior [-Waddress]
   if(c == "+"){
           ^~~
/in/foo.cc:8:11: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]