foo.cc: In function 'int main()':
foo.cc:9:17: warning: too many arguments for format [-Wformat-extra-args]
  printf("&.1f",c);
                 ^
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%f",&f);
  ~~~~~^~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务