Compilare: user.cpp: In function ‘void arity(int)’: user.cpp:78:17: warning: NULL used in arithmetic [-Wpointer-arith] while(*p != NULL) ^ user.cpp: In function ‘int main()’: user.cpp:111:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^ user.cpp:116:31: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s[0]), gets(s[1]); ^ user.cpp:116:31: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] /tmp/ccLKgbnc.o: In function `main': user.cpp:(.text.startup+0x4d): warning: the `gets' function is dangerous and should not be used.