Compilare: user.cpp: In function ‘int main()’: user.cpp:15:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++){ ^ user.cpp:18:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i+1;j<s.length();j++) s2+=s[j]; ^ user.cpp:22:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s1.length();i++){ ^ user.cpp:27:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while((s1[i]>='0' && s1[i]<='9')&& i<s1.length()){ ^ user.cpp:40:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s2.length();i++){ ^ user.cpp:45:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while((s2[i]>='0' && s2[i]<='9')&& i<s2.length()){ ^