Compilare: user.cpp: In function ‘int main()’: user.cpp:30:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(c != string::npos) { ^ user.cpp:26:9: warning: unused variable ‘len1’ [-Wunused-variable] int len1 = strlen(s1); ^ user.cpp:27:9: warning: unused variable ‘len2’ [-Wunused-variable] int len2 = strlen(s2); ^