Compilare: main.cpp: In function 'int main()': main.cpp:31:95: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("huffman.in","r",stdin),freopen("huffman.out","w",stdout),fread(u,1,M,stdin),n=B(); ^ main.cpp:31:95: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] main.cpp:31:95: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result]