Compilare: user.cpp: In function ‘int swap(int, int)’: user.cpp:16: warning: no return statement in function returning non-void user.cpp: In function ‘int main()’: user.cpp:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result