Main.cc: In function ‘int main()’: Main.cc:15:23: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘char (*)[100010]’ [-Wformat=] scanf("%s", &s); ~~^ Main.cc:18:31: error: request for member ‘size’ in ‘s’, which is of non-class type ‘char [100010]’ for (int i = 0; i < s.size(); i++) ^~~~ Main.cc:15:14: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", &s); ~~~~~^~~~~~~~~~