Compilare: user.cpp: In function ‘void postfix(std::__cxx11::string)’: user.cpp:25:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < str.size(); ++i) ~~^~~~~~~~~~~~ user.cpp: In function ‘void solve()’: user.cpp:89:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < aux.size(); ++i) ~~^~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:123:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < strlen(input) - 1; ++i) ~~^~~~~~~~~~~~~~~~~~~ user.cpp:129:60: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘__gnu_cxx::__alloc_traits<std::allocator<long long unsigned int> >::value_type {aka long long unsigned int}’ [-Wformat=] fprintf (fopen("evaluare.out", "w"), "%ld\n", fin.top()); ^ user.cpp: In function ‘int priority(char)’: user.cpp:19:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:121:53: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (input, 100004, fopen("evaluare.in", "r")); ^