Compilare: user.cpp: In function ‘double determinant(int)’: user.cpp:23:12: warning: unused variable ‘x1’ [-Wunused-variable] double x1,x2,x3,y1,y2,y3; ^ user.cpp:23:21: warning: unused variable ‘y1’ [-Wunused-variable] double x1,x2,x3,y1,y2,y3; ^ user.cpp: In function ‘int main()’: user.cpp:39:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d",&n); ^ user.cpp:44:45: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%lf%lf",&a[i].x,&a[i].y); ^