Compilare: main.cpp: In function 'int formnr()': main.cpp:10:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; i<s.size()&&s[i]>='0'&&s[i]<='9'; i++) ~^~~~~~~~~ main.cpp:14:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp: In function 'void codif()': main.cpp:17:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<s.size(); i++) ~^~~~~~~~~