Compilare: user.cpp: In function ‘int main()’: user.cpp:17:39: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] (void)fread(buff, 1, 20000, stdin); ^ user.cpp: In function ‘void read(long long unsigned int&)’: user.cpp:7:109: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] while(buff[pos] < '0' || buff[pos] > '9') if(++pos == 20000) (void)fread(buff, 1, 20000, stdin), pos = 0; ^ user.cpp:12:71: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if(++pos == 20000) (void)fread(buff, 1, 20000, stdin), pos = 0; ^