Answers to questions on static variables in functions

1. Write a function which has a single integer parameter and uses static integer variables to keep track of the mean of all values passed to it during the running of a program. It should return the mean so far each time it is called. Test it in a program.

   float mean_so_far(int val)
   {
      static int sum, number; /*Statics are set to zero initially*/
      sum = sum + val;
      number++;
      return sum / number;
   }
   

2. Why can this function only keep a running mean for one stream of values?

   Because there is only one instance of each of the stsic variables. It would be necessary to define a different version of the function, with a unique name, for each stream to be recorded. This weakness was one of the reasons for the extension into the use of objects.

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