Compilare: user.cpp: In function ‘int main()’: user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp:20: warning: comparison between signed and unsigned integer expressions user.cpp:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:13: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:15: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp:10: warning: ‘ok’ may be used uninitialized in this function /tmp/ccOqJKkf.o: In function `main': user.cpp:(.text+0x56): warning: the `gets' function is dangerous and should not be used.