Compilare: user.cpp: In function ‘int main()’: user.cpp:32:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (strlen(A) != N) while (1); ^ user.cpp:23:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.in", "r", stdin); ^ user.cpp:24:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.out", "w", stdout); ^ user.cpp:25:9: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(A); ^ user.cpp:29:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(A); ^ /tmp/cc0afEem.o: In function `main': user.cpp:(.text.startup+0x54): warning: the `gets' function is dangerous and should not be used.