Compilare: user.cpp: In member function ‘void Container::_mergesort(int, int)’: user.cpp:79:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(merged[ i ] < vec[ p2 ]) vec[ p1++ ] = merged[ i++ ]; ^ user.cpp: In function ‘int main()’: user.cpp:114:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < N; i++) { ^ user.cpp:100:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(FIN, "r", stdin); ^ user.cpp:102:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&N); ^ user.cpp:106:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets( str ); ^ /tmp/ccuMYucf.o: In function `main': user.cpp:(.text.startup+0x7f): warning: the `gets' function is dangerous and should not be used.