Compilare: user.cpp: In function ‘void adaug(trie*, char*)’: user.cpp:23:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^~~~ user.cpp: In function ‘int prefix(trie*, char*, int)’: user.cpp:39:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL or !t->fiu[ch] ) ^~~~ user.cpp: In function ‘int nr_ap(trie*, char*)’: user.cpp:48:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^~~~ user.cpp: In function ‘int del(trie*, char*)’: user.cpp:59:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) ^~~~ user.cpp: In function ‘int prefix(trie*, char*, int)’: user.cpp:44:1: warning: control reaches end of non-void function [-Wreturn-type] } ^