Compilare: user.cpp: In function ‘bool NOT(char, char)’: user.cpp:27:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘bool VAL(char, char)’: user.cpp:42:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:89:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("bool.in", "r", stdin); ^ user.cpp:90:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("bool.out", "w", stdout); ^ user.cpp:92:13: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (s); ^ user.cpp:95:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d ", &N); ^ user.cpp:98:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%c", &C); ^ /tmp/cclaMPRG.o: In function `main': user.cpp:(.text.startup+0x5e): warning: the `gets' function is dangerous and should not be used.