Compilare: user.cpp: In function ‘void adauga(trie*, char*)’: user.cpp:23:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^ user.cpp: In function ‘int del(trie*, char*)’: user.cpp:38:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^ user.cpp: In function ‘int nr_apar(trie*, char*)’: user.cpp:60:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^ user.cpp: In function ‘int pre(trie*, char*, int)’: user.cpp:69:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL||!nod->fiu[*s-'a']) ^ user.cpp:72:1: warning: control reaches end of non-void function [-Wreturn-type] } ^