Compilare: user.cpp: In function ‘void nru(int&)’: user.cpp:14:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<in.size()&&isdigit(in[i])) ^ user.cpp:19:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i<in.size()) i--; ^ user.cpp: In function ‘int main()’: user.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<in.size();i++) ^ user.cpp:24:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,a,b; ^