Compilare: main.cpp: In function 'int getInt(std::__cxx11::string&, int&)': main.cpp:25:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (pos < s.length() && isdigit (s[pos])) ret *= 10, ret += s[pos++] - '0'; ~~~~^~~~~~~~~~~~ main.cpp: In function 'std::__cxx11::string getPolishForm(std::__cxx11::string)': main.cpp:43:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (pos < s.length()) { ~~~~^~~~~~~~~~~~ main.cpp: In function 'void setFunctionSyntax(std::__cxx11::string&)': main.cpp:75:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (pos < s.length() && s[pos] != '=') ++pos; ~~~~^~~~~~~~~~~~ main.cpp: In function 'int evaluatePolish(std::vector<int>&, std::__cxx11::string&)': main.cpp:97:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (pos < s.length()) { ~~~~^~~~~~~~~~~~ main.cpp: In function 'int evaluateFunction(std::__cxx11::string&, int&)': main.cpp:123:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (pos < s.length() && s[pos] != ')') { ~~~~^~~~~~~~~~~~