foo.cc: In function 'int main()':
foo.cc:13:3: error: duplicate case value
   case '+':
   ^~~~
foo.cc:10:3: note: previously used here
   case '+':
   ^~~~
foo.cc:27:2: error: expected ';' before 'return'
  return 0;
  ^~~~~~
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%f,%f,%c",&a,&b,&c);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~

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