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  Keyword:  struct
 
  Syntax:   struct [tag] {member-declaration-list} [declarators];
            struct tag declarators;
 
  Summary:  Declares a structure type and/or a structure variable.
 
     If braces are given, a structure type is defined. Items in
     <member-declaration-list> can be any valid declaration (including
     other structures), or they can be bit fields in the following
     form:
 
          int-type-specifier [identifier] : constant-expression
 
     The <int-type-specifier> must be a signed or unsigned integer or
     long integer. The <constant-expression> specifies the number of
     bits in the field. Unnamed bit fields can be used for alignment.
     If an unnamed field has width 0, the next field is aligned on the
     current packing boundary as defined by /zp or #pragma pack.
 
     A non-ANSI extension allows the last member of the structure to be
     a zero-length array.
 
     If braces are not given, the struct keyword is used to define a
     structure variable. The tag identifies the type.
 
     Structure variables can be initialized. The initialization for
     each variable must be enclosed in braces. For example,
 
     struct POINT            // Declare POINT structure
     {
         int x;              // Define members x and y
         int y;
     } here = { 20, 40 };    // Variable here has valued x = 20, y = 40
     struct POINT there;     // Variable there has POINT type
     struct CELL             // Declare COLOR bit field
     {
         unsigned character  : 8;                  // 00000000 ????????
         unsigned foreground : 3;                  // 00000??? 00000000
         unsigned intensity  : 1;                  // 0000?000 00000000
         unsigned background : 3;                  // 0???0000 00000000
         unsigned blink      : 1;                  // ?0000000 00000000
     } screen[25][80];       // Array of bit fields
 
     A non-ANSI extension allows structs to be defined without
     declarators when they are members of another struct or a union.
     This allows the members to be referenced as if they were declared
     directly in the containing struct or union. For example,
 
          struct phone
          {
             int  areacode;
             long number;
          };
 
          struct person
          {
             char   name[30];
             char   sex;
             int    age;
             int    weight;
             struct phone;
          } Jim;
 
          Jim.number = 1234567;
 
     Another non-ANSI extension allows the last member of a struct to
     be a variable-length array, by declaring it to be an unsized (or
     zero sized) array. Such a struct may appear in other structs, as
     long as it is the last member declared in the enclosing struct.
 
     If a variable declared as such a struct is uninitialized, or if no
     initializer is present for the unsized array member, no space is
     allocated for the array, and references to it give undefined
     results. If an initializer is present, enough space is allocated
     to store the elements specified. If the initializer is a string
     literal, space for the trailing \0 is included; if it is a list
     of character constants, no extra character is added.
 
     When the sizeof operator is applied to such a struct, it assumes
     the array to be of length 0, so the full size of the struct must
     be determined by other means. When allocating new structs of this
     type using malloc, the number of bytes requested must be equal to
     or greater than the value returned by sizeof. For structs
     allocated in this manner, the length of the array is determined
     by the amount of additional memory requested.
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