/in/compound.cpp: In member function 'double Compound::calculateMolarMass()':
/in/compound.cpp:6:1: error: no return statement in function returning non-void [-Werror=return-type]
 }
 ^
/in/compound.cpp: In constructor 'Compound::Compound(int*, int)':
/in/compound.cpp:8:26: error: unused parameter 'arr' [-Werror=unused-parameter]
 Compound:: Compound(int* arr, int num){
                          ^~~
/in/compound.cpp:8:35: error: unused parameter 'num' [-Werror=unused-parameter]
 Compound:: Compound(int* arr, int num){
                                   ^~~
/in/compound.cpp: In member function 'std::__cxx11::string Compound::toString()':
/in/compound.cpp:15:1: error: no return statement in function returning non-void [-Werror=return-type]
 }
 ^
/in/compound.cpp: At global scope:
/in/compound.cpp:22:18: error: redefinition of 'const int MAX_ELEM'
 static int const MAX_ELEM = 30;
                  ^~~~~~~~
In file included from /in/compound.cpp:3:0:
/in/compile/compound.h:6:18: note: 'const int MAX_ELEM' previously defined here
 static int const MAX_ELEM = 30;
                  ^~~~~~~~
/in/compound.cpp:23:18: error: redefinition of 'const int MAX_NUM_ELEM'
 static int const MAX_NUM_ELEM = 118; 
                  ^~~~~~~~~~~~
In file included from /in/compound.cpp:3:0:
/in/compile/compound.h:7:18: note: 'const int MAX_NUM_ELEM' previously defined here
 static int const MAX_NUM_ELEM = 118;
                  ^~~~~~~~~~~~
/in/compound.cpp:25:7: error: redefinition of 'class Element'
 class Element{
       ^~~~~~~
In file included from /in/compound.cpp:3:0:
/in/compile/compound.h:9:7: note: previous definition of 'class Element'
 class Element{
       ^~~~~~~
/in/compound.cpp:39:7: error: redefinition of 'class Compound'
 class Compound{
       ^~~~~~~~
In file included from /in/compound.cpp:3:0:
/in/compile/compound.h:23:7: note: previous definition of 'class Compound'
 class Compound{
       ^~~~~~~~
/in/compound.cpp:66:1: error: expected unqualified-id at end of input
 }
 ^
cc1plus: all warnings being treated as errors