Compilare: user.cpp: In function ‘int main()’: user.cpp:19:14: warning: NULL used in arithmetic [-Wpointer-arith] if ((*p1==NULL && *p2==' ') || (*p1==' ' && *p2==' ') || (*p1==' ' && *p2==NULL) || (*p1==NULL && *p2==NULL)) ^ user.cpp:19:79: warning: NULL used in arithmetic [-Wpointer-arith] if ((*p1==NULL && *p2==' ') || (*p1==' ' && *p2==' ') || (*p1==' ' && *p2==NULL) || (*p1==NULL && *p2==NULL)) ^ user.cpp:19:94: warning: NULL used in arithmetic [-Wpointer-arith] if ((*p1==NULL && *p2==' ') || (*p1==' ' && *p2==' ') || (*p1==' ' && *p2==NULL) || (*p1==NULL && *p2==NULL)) ^ user.cpp:19:107: warning: NULL used in arithmetic [-Wpointer-arith] if ((*p1==NULL && *p2==' ') || (*p1==' ' && *p2==' ') || (*p1==' ' && *p2==NULL) || (*p1==NULL && *p2==NULL)) ^ user.cpp:25:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<strlen(a);i++) ^