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Synopsis:
    #include <stddef.h>
    size_t offsetof( composite, name );

Description:
    The offsetof macro returns the offset of the element name within the
     struct or  union composite.  This provides a portable method to
    determine the offset.

Returns:
    The offsetof function returns the offset of name.

Example:
    #include <stdio.h>
    #include <stddef.h>

    struct new_def
    {  char *first;
       char second[10];
       int third;
    };

    void main()
      {
        printf( "first:%d second:%d third:%d\n",
            offsetof( struct new_def, first ),
            offsetof( struct new_def, second ),
            offsetof( struct new_def, third ) );
      }

    produces the following:

    In a small data model, the following would result:

    first:0 second:2 third:12

    In a large data model, the following would result:

    first:0 second:4 third:14

Classification:
    ANSI

Systems:
    MACRO