Compilare: user.cpp: In function ‘int main()’: user.cpp:28:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<=strlen(s);++j) ^ user.cpp:21:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:27:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccN1qY8r.o: In function `main': user.cpp:(.text.startup+0xad): warning: the `gets' function is dangerous and should not be used.