/in/foo.cc: In function 'int main()':
/in/foo.cc:26:15: warning: array subscript has type 'char' [-Wchar-subscripts]
  for( i=0;s1[i]!=0;i++)
               ^
/in/foo.cc:28:12: warning: array subscript has type 'char' [-Wchar-subscripts]
   cin>>s1[i];
            ^
/in/foo.cc:30:15: warning: array subscript has type 'char' [-Wchar-subscripts]
  for( i=0;s2[i]!=0;i++)
               ^
/in/foo.cc:32:12: warning: array subscript has type 'char' [-Wchar-subscripts]
   cin>>s2[i];
            ^
/in/foo.cc:26:15: warning: 's1[0]' is used uninitialized in this function [-Wuninitialized]
  for( i=0;s1[i]!=0;i++)
           ~~~~^