Compilare: user.cpp: In function ‘int main()’: user.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(s);i++) ^ user.cpp:71:14: warning: statement has no effect [-Wunused-value] for(i;i<strlen(s);i++) ^ user.cpp:71:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i;i<strlen(s);i++) ^