By-
Aakash
Aayush Nigam
Abhinav Porwal

A data type is a class of data objects with a set of
operations for creating
and manipulating them. Examples of elementary data
types: integer, real, character, Boolean, enumeration,
pointer.

 Numeric Data Types
 Enumerations
 Boolean
 Characters
 Character Strings
 Pointers & Programmer-
Constructed Data Objects
 Files & Input-Output

NUMERIC DATA TYPES
• A numeric <data type> is defined by a descriptor that contains four pieces
of information:
• The <data type>'s name:
either INTEGER, SMALLINT, NUMERIC, DECIMAL, FLOAT, REAL or DOUBL
E PRECISION.
• The <data type>'s precision.
• The <data type>'s scale (for exact numeric types).
Whether the <data type>'s precision and scale are expressed in decimal or
binary terms.

Integers Sub-ranges
Floating-
Point Real
Number
Fixed-Point
Real
Number

 INTEGERS
In computer science, an integer is a datum
of integral data type, a data type that
represents some finite subset of the
mathematical integers.
Integral data types may be of different sizes
and may or may not contain negative values.
Cont.

Maximal and minimal
values. The maximum
integer value is
sometimes represented
as a defined constant (eg-
in Pascal, it is the
constant maxint.)
• Arithmetic Operations
• Relational Operations
• Assignment Operations
• Bit Operations
Hardware defined.

 SUBRANGES
A subrange type defines a subset of the
values of a particular type. By using
subrange types, you can easily detect errors
occuring due to unreasonable values of a
variable which shouldn't take values outside
a given boundary. Subrange types can be
defined of type character, integer, in no case
real!
Cont.

Subtype of integer
A sequence of integer
values within some
restricted range
Pascal declaration A: 1..10
means that the variable
A may be assigned integer
Values from 1 through 10.
Smaller storage requirement, better type checking

 FLOATING-POINT REAL NUMBERS
The encoding scheme for floating point
numbers is more complicated than for
fixed point. The basic idea is the same as
used in scientific notation, where a mantissa
is multiplied by ten raised to some
exponent. For instance, 5.4321 × 106,
where 5.4321 is the mantissa and 6 is the
exponent.
Cont.

Minimum and maximal
value
Round-off issues – the
check for equality may fail
due to round-off.
• Arithmetic Operations
• Relational Operations
• Assignment Operations
• Bit Operations
Mantissa – exponent model.
Example: 10.5 = 0.105 x 10,
Mantissa: 105, Exponent:2

 FIXED-POINT REAL NUMBERS
In computing, a fixed-point
number representation is a real data type
for a number that has a fixed number of
digits after (and sometimes also before) the
radix point(after the decimal point '.' in
English decimal notation).
Cont.

Real numbers with
predefined decimal
places
• Arithmetic Operations
• Relational Operations
• Assignment Operations
• Bit Operations
Directly supported by hardware or simulated by software

Involves a complex data structure organization by the
compiler.
Character
Strings
Pointers &
Programmer
Constructed
Data Objects
Files and
Input-Output
TYPES

In computer programming, a string is
traditionally a sequence of characters, either
as a literal constant or as some kind of
variable. The latter may allow its elements
to be mutated and the length changed, or it
may be fixed (after creation).
Cont.

Cont.
• Fixed declared length: storage allocation at
translation time. Strings longer than the
declared length are truncated.
• Variable length to a declared bound: storage
allocation at translation time. An upper bound
for length is set and any string over that length
is truncated.
• Unbound length: storage allocation at run
time. String can be of any length with in the
range.

Cont.
• Concatenation – appending two strings
• Relational – equal(=), less than(<), greater
than(>)
• Substring selection – using positioning
subscripts
• Substring selection – using pattern matching
• Input/output formatting
• Dynamic strings – the string is evaluated at
run time.

• Fixed declared length: A packed vector of
characters
• Variable length to a declared bound: a
descriptor that contains the maximum length
and the current length
• Unbound length: Either a linked storage of
fixed-length data objects or a contiguous array
of characters with dynamic run-time storage
allocation.