Compilare: user.cpp: In function ‘void read(int&)’: user.cpp:19:67: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if(pos==buf_size) pos=0, fread(buf, 1, sizeof(buf), stdin); ^ user.cpp:26:67: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if(pos==buf_size) pos=0, fread(buf, 1, sizeof(buf), stdin); ^ user.cpp: In function ‘int main()’: user.cpp:62:38: 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); ^ user.cpp:63:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("huffman.out", "w", stdout); ^ user.cpp:65:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] pos=0, fread(buf, 1, sizeof(buf), stdin); ^