Compilare: user.cpp: In function ‘int main()’: user.cpp:13:17: warning: unused variable ‘i’ [-Wunused-variable] int v[MAX], n, i; ^ user.cpp: In function ‘void polish(char*, std::vector<char>, int*, int*)’: user.cpp:26:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < strlen(expr); i++){ ^ user.cpp:51:12: warning: value computed is not used [-Wunused-value] v[*n] == s.back() - 48; ^ user.cpp: In function ‘int main()’: user.cpp:15:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", expr); ^