Compilare: user.cpp: In function ‘std::string prev1(int, std::string)’: user.cpp:24:14: warning: statement has no effect [-Wunused-value] for(i; i<n; ++i) ^ user.cpp: In function ‘std::string next1(int, std::string)’: user.cpp:42:14: warning: statement has no effect [-Wunused-value] for(i; i<n; ++i){ ^ user.cpp:49:20: warning: value computed is not used [-Wunused-value] else s[n-1]=='0'; ^ user.cpp: In function ‘std::string prev1(int, std::string)’: user.cpp:30:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘std::string next1(int, std::string)’: user.cpp:57:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:77:17: warning: ‘c’ may be used uninitialized in this function [-Wmaybe-uninitialized] g<<c; ^