Compilare: user.cpp: In instantiation of ‘nrx_segment_tree<Type>::tree_node::tree_node() [with Type = int]’: user.cpp:82:8: required from here user.cpp:93:35: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] lazy = sum = type = NULL; ^ user.cpp: In instantiation of ‘void nrx_segment_tree<Type>::reset_tree(nrx_segment_tree<Type>::tree_node*) [with Type = int]’: user.cpp:383:30: required from ‘void nrx_segment_tree<Type>::build_tree(Type*, Type*) [with Type = int]’ user.cpp:432:50: required from here user.cpp:109:90: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] node -> left_son = node -> right_son = NULL; node -> lazy = node -> type = NULL; ^ user.cpp:110:73: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] node -> minim = +INF; node -> maxim = -INF; node -> sum = NULL; ^ user.cpp: In function ‘int main()’: user.cpp:426:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("arbint.out","w", stdout); ^ user.cpp: In constructor ‘nrx_input_reader::nrx_input_reader(const char*, const char*, int)’: user.cpp:23:74: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] buffer = new char[SIZE]; fread( buffer, SIZE, 1, input_file ); ^ user.cpp: In member function ‘void nrx_input_reader::advance()’: user.cpp:16:53: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread( buffer, SIZE, 1, input_file ); ^