Compilare: user.cpp: In function ‘int main()’: user.cpp:19:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<strlen(s);i++) ^ user.cpp:22:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<strlen(s);i++) ^ user.cpp:42:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<strlen(s);i++) ^ user.cpp:49:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<strlen(s);i++) ^