Compilare: user.cpp: In function ‘int sir(char*)’: user.cpp:22:17: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] t[3]=NULL; ^ user.cpp:35:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) return 1; ^ user.cpp: In function ‘int sirr(char*)’: user.cpp:50:12: warning: NULL used in arithmetic [-Wpointer-arith] if(*s==NULL) return 1; else return 0; ^