Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:24: error: ‘strrev’ was not declared in this scope user.cpp:6: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:7: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:8: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result