Page 75 - DCAP201_FUNDAMENTALS_OF_DATA_STRUCTURES

Fundamentals of Data Structures

Notes 5.2.2 Static Initialisation of Pointer Arrays

Initialisation of arrays of pointers is an ideal application for an internal static array.
some_fn()
{ static char *months = { “no month”,
“jan”, “feb”,
...};
}
static reserves a private permanent bit of memory.

Task Write a C program to read through an array of any type using pointers.

Self Assessment

Fill in the blanks:

6. .............................. are a data representation that will cope efficiently and conveniently with
variable length text lines.
7. A 2D array is really a .............................. array, each of whose elements is itself an array.

8. C needs to know how many .............................. in order that it can jump from row to row in
memory.
9. Initialisation of arrays of pointers is an ideal application for an internal ..................... array.

10. .............................. elements are stored row by row.

5.3 Records and Record Structures

As we studied already that the collections of data are frequently organized into a hierarchy of
field, records and files. Specifically a record is a collection of related data items, each of which is
called a field or attribute, and a file is a collection of similar records. Each data item itself may be
a group item composed of sub items; those items which are indecomposable are called elementary
items or atoms or scalars. The names given to the various data items are called identifiers.
As we know that a record is a collection of data items, it differs from a linear array in the
following way,
(a) A record may be a collection of non-homogeneous data; i.e. the data items in a record may
have different data types.

(b) The data items in a record are indexed by attribute names, so there may not be a natural
ordering of its elements.
Under the relationship of group item to sub item, the data items in a record form a hierarchical
structure which can be described by means of “level” numbers. Let we understand through the
following examples.

Example:

Consider a hospital keeps a record on each newborn baby who contains the following data
items: Name, Sex, Birthday, Father, and Mother. Assume that Birthday is a group item with sub

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