Compilare: user.cpp: In function ‘void read(int&)’: user.cpp:54: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result user.cpp:60: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:67: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:68: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:98: warning: ‘idx’ may be used uninitialized in this function user.cpp:116: warning: ‘idx’ may be used uninitialized in this function