Eroare de compilare: main.cpp:14:12: error: 'double y1' redeclared as different kind of symbol double x1, y1, x2, y2, alfa; ^~ In file included from /usr/include/features.h:367:0, from /usr/include/x86_64-linux-gnu/c++/6/bits/os_defines.h:39, from /usr/include/x86_64-linux-gnu/c++/6/bits/c++config.h:507, from /usr/include/c++/6/iostream:38, from main.cpp:1: /usr/include/x86_64-linux-gnu/bits/mathcalls.h:251:1: note: previous declaration 'double y1(double)' __MATHCALL (y1,, (_Mdouble_)); ^ main.cpp: In function 'int main()': main.cpp:24:13: error: no match for 'operator>>' (operand types are 'std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}' and 'double(double) throw ()') f >> x1 >> y1 >> x2 >> y2; ~~~~~~~~^~~~~ In file included from /usr/include/c++/6/iostream:40:0, from main.cpp:1: /usr/include/c++/6/istream:120:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match> operator>>(__istream_type& (*__pf)(__istream_type&)) ^~~~~~~~ /usr/include/c++/6/istream:120:7: note: conversion of argument 1 would be ill-formed: main.cpp:24:16: error: invalid conversion from 'double (*)(double) throw ()' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&) {aka std::basic_istream<char>& (*)(std::basic_istream<char>&)}' [-fpermissive] f >> x1 >> y1 >> x2 >> y2; ^~ In file included from /usr/include/c++/6/iostream:40:0, from main.cpp:1: /usr/include/c++/6/istream:124:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>; std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>] <near match> operator>>(__ios_type& (*__pf)(__ios_type&)) ^~~~~~~~ /usr/include/c++/6/istream:124:7: note: conversion of argument 1 would be ill-formed: main.cpp:24:16: error: invalid conversion from 'double (*)(double) throw ()' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}' [-fpermissive] f >> x1 >> y1 >> x2 >> y2; ^~ In file included from /usr/include/c++/6/iostream:40:0, from main.cpp:1: /usr/include/c++/6/istream:131:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match> operator>>(ios_base& (*__pf)(ios_base&)) ^~~~~~~~ /usr/include/c++/6/istream:131:7: note: conversion of argument 1 would be ill-formed: main.cpp:24:16: error: invalid conversion from 'double (*)(double) throw ()' to 'std::ios_base& (*)(std::ios_base&)' [-fpermissive] f >> x1 >> y1 >> x2 >> y2; ^~ In file included from /usr/include/c++/6/iostream:40:0, from main.cpp:1: /usr/include/c++/6/istream:168:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match> operator>>(bool& __n) ^~~~~~~~ /usr/include/c++/6/istream:168:7: note: conversion of argument 1 would be ill-formed: main.cpp:24:16: warning: the address of 'double y1(double)' will always evaluate as 'true' [-Waddress] f >> x1 >> y1 >> x2 >> y2; Non zero exit status: 1