Compilare: user.cpp: In function ‘int main()’: user.cpp:152:13: warning: variable ‘III’ set but not used [-Wunused-but-set-variable] int op, III; ^~~ user.cpp:149:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("secv8.in", "r", stdin); ^ user.cpp:150:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("secv8.out", "w", stdout); ^ user.cpp: In function ‘char next()’: user.cpp:29:41: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, BUF, fin), pos = 0; ^