Compilare: main.cpp: In member function 'bool ExprEvaluator::isOperator(char)': main.cpp:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < this->OPERATORS.size(); i++) { ~~^~~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'int ExprEvaluator::opPriority(char)': main.cpp:32:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < this->OPERATORS.size(); i++) { ~~^~~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'int ExprEvaluator::evaluateExpr(const string&)': main.cpp:62:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (expr_pos < expr.size()) { ~~~~~~~~~^~~~~~~~~~~~~ main.cpp:69:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (expr_pos < expr.size() && isdigit(expr[expr_pos])) { ~~~~~~~~~^~~~~~~~~~~~~