Compilare: user.cpp: In function ‘double ev()’: user.cpp:18:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p<s.size() && (s[p]=='-' || s[p]=='+')) ^ user.cpp: In function ‘double fact()’: user.cpp:26:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p<s.size() && (s[p]=='*' || s[p]=='/')) ^ user.cpp: In function ‘double term()’: user.cpp:36:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p<s.size() && s[p]<='9' && s[p]>='0') ^ user.cpp: At global scope: user.cpp:41:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^