Compilare: user.cpp: In function ‘int main()’: user.cpp:94:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unicat.in", "r", stdin); ^ user.cpp:95:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unicat.out", "w", stdout); ^ user.cpp:104:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a + 1); ^ user.cpp:105:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(b + 1); ^ /tmp/ccXFkgbR.o: In function `main': user.cpp:(.text.startup+0x100): warning: the `gets' function is dangerous and should not be used.