Compilare: user.cpp: In function ‘int main()’: user.cpp:16:12: warning: variable ‘X1’ set but not used [-Wunused-but-set-variable] double X1, Y1, X2, Y2; ^ user.cpp:16:16: warning: variable ‘Y1’ set but not used [-Wunused-but-set-variable] double X1, Y1, X2, Y2; ^ user.cpp:16:20: warning: variable ‘X2’ set but not used [-Wunused-but-set-variable] double X1, Y1, X2, Y2; ^ user.cpp:16:24: warning: variable ‘Y2’ set but not used [-Wunused-but-set-variable] double X1, Y1, X2, Y2; ^ user.cpp:20:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &n); ^ user.cpp:21:83: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=0; i<n; i++) fscanf(fin, "%lf%lf%lf%lf", &a1[i], &b1[i], &a2[i], &b2[i]); ^