foo.cpp: In function 'double calcdistance(Circle&, Circle&)':
foo.cpp:21:38: error: 'pow' was not declared in this scope
foo.cpp:21:72: error: 'pow' was not declared in this scope
foo.cpp:21:72: error: redeclaration of '<typeprefixerror>pow'
foo.cpp:21:38: note: previous declaration '<typeprefixerror>pow'
foo.cpp: In function 'int main()':
foo.cpp:33:7: warning: unused variable 'pdis' [-Wunused-variable]
foo.cpp: In function 'double calcdistance(Circle&, Circle&)':
foo.cpp:22:1: warning: control reaches end of non-void function [-Wreturn-type]