Eroare de compilare: user.cpp:11:20: error: ‘double y1’ redeclared as different kind of symbol double x1,x2,x3,x4,y1,y2,y3,y4,xg,yg; ^ In file included from /usr/include/features.h:346:0, from /usr/local/include/c++/4.8.0/i686-pc-linux-gnu/bits/os_defines.h:39, from /usr/local/include/c++/4.8.0/i686-pc-linux-gnu/bits/c++config.h:420, from /usr/local/include/c++/4.8.0/iosfwd:38, from /usr/local/include/c++/4.8.0/ios:38, from /usr/local/include/c++/4.8.0/istream:38, from /usr/local/include/c++/4.8.0/fstream:38, from user.cpp:1: /usr/include/bits/mathcalls.h:242:1: error: previous declaration of ‘double y1(double)’ __MATHCALL (y1,, (_Mdouble_)); ^ user.cpp: In function ‘int main()’: user.cpp:44:25: error: assignment of function ‘double y1(double)’ x1=v[i].x;y1=v[i].y; ^ user.cpp:44:25: error: cannot convert ‘double’ to ‘double(double)throw ()’ in assignment user.cpp:46:35: error: invalid operands of types ‘double(double)throw ()’ and ‘double’ to binary ‘operator+’ xg=(x1+x3)/2.0;yg=(y1+y3)/2.0; ^