Eroare de compilare: user.cpp:6:13: error: ‘int y1’ redeclared as different kind of symbol int n,x1,x2,y1,y2,i,nr,j,a[550],b,c; ^ In file included from /usr/include/features.h:357:0, from /usr/include/i386-linux-gnu/c++/4.8/bits/os_defines.h:39, from /usr/include/i386-linux-gnu/c++/4.8/bits/c++config.h:420, from /usr/include/c++/4.8/cstdio:41, from user.cpp:1: /usr/include/i386-linux-gnu/bits/mathcalls.h:243:1: error: previous declaration of ‘double y1(double)’ __MATHCALL (y1,, (_Mdouble_)); ^ user.cpp: In function ‘int main()’: user.cpp:15:46: warning: format ‘%d’ expects argument of type ‘int*’, but argument 3 has type ‘double (*)(double)throw ()’ [-Wformat=] scanf("%d %d %d %d\n",&x1,&y1,&x2,&y2); ^ user.cpp:16:14: warning: pointer to a function used in arithmetic [-Wpointer-arith] b=y1-y2; ^ user.cpp:16:13: error: invalid conversion from ‘double (*)(double)throw ()’ to ‘int’ [-fpermissive] b=y1-y2; ^ user.cpp:10:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("geometry.in","r",stdin); ^ user.cpp:11:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("geometry.out","w",stdout); ^ user.cpp:12:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:15:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n",&x1,&y1,&x2,&y2); ^