Compilare: user.cpp: In function ‘int operatie()’: user.cpp:14:15: warning: NULL used in arithmetic [-Wpointer-arith] while(*p!=NULL && (*p == '+' || *p == '-')){ ^ user.cpp: In function ‘int factor()’: user.cpp:29:15: warning: NULL used in arithmetic [-Wpointer-arith] while(*p!=NULL && (*p == '*' || *p == '/')){ ^ user.cpp: In function ‘int element()’: user.cpp:51:19: warning: NULL used in arithmetic [-Wpointer-arith] while(*p!=NULL && strchr("123456790",*p)!=NULL){ ^ user.cpp: In function ‘int main()’: user.cpp:62:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.in","r",stdin); ^ user.cpp:63:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.out","w",stdout); ^