Initialization of Pointer Arrays in C

By: Baski

Consider the problem of writing a function month_name(n), which returns a pointer to a character string containing the name of the n-th month. This is an ideal application for an internal static array. month_name contains a private array of character strings, and returns a pointer to the proper one when called. This section shows how that array of names is initialized.

The declaration of name, which is an array of character pointers, is the same as lineptr in the sorting example. The initializer is a list of character strings; each is assigned to the corresponding position in the array. The characters of the i-th string are placed somewhere, and a pointer to them is stored in name[i]. Since the size of the array name is not specified, the compiler counts the initializers and fills in the correct number.

   /* month_name:  return name of n-th month */
   char *month_name(int n)
   {
       static char *name[] = {
           "Illegal month",
           "January", "February", "March",
           "April", "May", "June",
           "July", "August", "September",
           "October", "November", "December"
       };

       return (n < 1 || n > 12) ? name[0] : name[n];
   }