Compilare: main.cpp: In function 'void Do()': main.cpp:36:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) { ~~^~~~~~~~~~ main.cpp:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while( i < s.size() && isdigit( s[i] ) ) { ~~^~~~~~~~~~ main.cpp: In function 'int Operate(int, int, char)': main.cpp:27:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.cpp: In function 'int Priority(char)': main.cpp:33:1: warning: control reaches end of non-void function [-Wreturn-type] } ^