Compilare: main.cpp: In function 'std::__cxx11::string replaceOperators(std::__cxx11::string)': main.cpp:23:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(found!=string::npos) ~~~~~^~~~~~~~ main.cpp:29:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(found!=string::npos) ~~~~~^~~~~~~~ main.cpp:35:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(found!=string::npos) ~~~~~^~~~~~~~ main.cpp:41:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(found!=string::npos) ~~~~~^~~~~~~~ main.cpp:47:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(found!=string::npos) ~~~~~^~~~~~~~ main.cpp: In function 'std::__cxx11::string infixToPostFix(std::__cxx11::string)': main.cpp:74:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<a.size();i++) ~^~~~~~~~~ main.cpp: In function 'void buildIndexTable(std::__cxx11::string)': main.cpp:107:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<a.size();i++) ~^~~~~~~~~ main.cpp: In function 'std::__cxx11::string replaceVariables(std::__cxx11::string)': main.cpp:118:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<a.size();i++) ~^~~~~~~~~ main.cpp: In function 'bool evaluate(std::__cxx11::string)': main.cpp:129:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<a.size();i++) ~^~~~~~~~~