Compilare: user.cpp: In function ‘int main()’: user.cpp:34:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( i = 0 ; i < v. size(); i++) ^ user.cpp:36:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( j = i + 1 ; j < v. size() ; j ++) ^ user.cpp:42:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( i = 1; i < v2.size() ; i ++) ^ user.cpp:25:12: warning: unused variable ‘P2’ [-Wunused-variable] POINT P1,P2; ^ user.cpp:26:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in","r",stdin); ^ user.cpp:27:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out","w",stdout); ^ user.cpp:28:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:31:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf",&P1.x,&P1.y); ^