error warning

[and09]

In file included from main.cpp:2:
./Genetic.h:23:20: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions]
int MaxIterations = 100;
^
./Genetic.h:24:20: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions]
int MaxPopulation = 100;
^
./Genetic.h:29:26: warning: in-class initialization of non-static data member is a C++11 extension [-Wc++11-extensions]
bool DoubleCrossingover = false;
^
main.cpp:5:1: error: 'main' must return 'int'
void main()
^~~~
int
main.cpp:16:37: error: expected expression
sort(solves.begin(), solves.end(), [](Polynom &a, Polynom &b) -> bool {return a.StandardDeviation < b.St...
^
main.cpp:24:8: error: call to 'abs' is ambiguous
if (abs(solves[c].Coefficients[i]) > 0.01)
^~~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/stdlib.h:129:6: note:
candidate function
int abs(int) __pure2;
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cstdlib:167:44: note:
candidate function
inline _LIBCPP_INLINE_VISIBILITY long abs( long __x) _NOEXCEPT {return labs(__x);}
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cstdlib:169:44: note:
candidate function
inline _LIBCPP_INLINE_VISIBILITY long long abs(long long __x) _NOEXCEPT {return llabs(__x);}
^
3 warnings and 3 errors generated.