Data Types
I.Mona Alshehri
Data Types:
Data Type: A set of values together with a set of operations is
called a data type.
C++ data types fall into three categories
•Simple Data Type.
•Structured Data Type.
•Pointers.
Simple Data Type:
C++ simple data can be classified into three categories:
1. Integral, which is a data type that deals with integers, or
numbers without a decimal part.
2. Floating-point, which is a data type that deals with decimal
numbers.
3. Enumeration type, which is a user-defined data type.
Integral data types:
Memory allocated for simple data types:
Simple Data Types:
char Data Type
char is the smallest integral data type.
char data type is used to represent characters, that is
letters, digits and special symbols.
Each character is enclosed within single quote marks.
Some of the values belonging to char data type are:
'A', 'a', '0', '*', '+', '$', '&'
Blank space is a character and is written ' ', with a space left
between the single quotes.
•Example:
char blank = ' ';
Simple Data Types:
bool Data Type
• The data type bool has two values, true and false.
• The central purpose of this data type is to
manipulate logical (Boolean) expressions. We call
true and false the logical (Boolean) values.
• In C++, bool, true, and false are reserved words.
• Example:
bool b = false;
Simple Data Types:
int Data Type
-6728, -67, 0, 78, 36782, +763,...
• The memory allocated for the int, unsigned int, long and
unsigned long data types are 4 bytes.
• Positive integers do not have to have a + sign in front of
them.
• No commas are used within an integer.
Example
int num;
long num;
Unsigned int num;
Simple Data Types:
Floating-Point Data Types:
• Scientific notation
43872918 = 4.3872918 *10^7
.0000265 = 2.65 * 10^(-5)
47.9832 = 4.7983 * 10^1
{10 to the power of seven},
{10 to the power of minus five},
{10 to the power of one}
• There are two notation to represent real numbers in C++:
1. Decimal notation
2. Exponential notation
Floating-Point Data Types:
• float: The data type float is used in C++ to represent any real
number between -3.4E+38 and 3.4E+38.The memory allocated
for the float data type is 4 bytes.
• double: The data type double is used in C++ to represent any
real number between -1.7E+308 and 1.7E+308.The memory
allocated for the double data type is 8 bytes.
Example
float conversion = 2.54;
double payRate = 0.45e-4;
Rules for defining variable name:
• A variable name can have one or more letters or digits or underscore
for example character _.
• White space, punctuation symbols or other characters are not
permitted to denote variable name. .
• A variable name must begin with a letter.
• Variable names cannot be keywords or any reserved words of the
C++ programming language.
• C++ is a case-sensitive language. Variable names written in capital
letters differ from variable names with the same name but written in
small letters. For example, the variable name EXFORSYS differs from
the variable name exforsys.
Declaring Variables:
In order for a variable to be used in C++ programming language, the
variable must first be declared. The syntax for declaring variable names is
data type variable name;
The date type can be int or float or any of the data types listed above. A
variable name is given based on the rules for defining variable name (refer
above rules).
Example:
int a;
This declares a variable name a of type int.
If there exists more than one variable of the same type, such variables
can be represented by separating variable names using comma.
For instance
int x,y,z
This declares 3 variables x, y and z all of data type int.
Declaring Conastant:
•Constants have fixed value. Constants, like variables, contain data type.
•In C++, const is a reserved word.
•A memory location whose content is not allowed to change during
program execution.
•The syntax to declare a named constant is:
const dataType identifier = value;
Example 2-11
const double conversion = 2.54;
const int noOfStudents = 20;
const char blank = ' ';
const double payRate = 15.75;
Lab Work:
Write a C++ program which reads an
integer number that represents number
of minutes and display the equivalent
number of hours.
Type Casting:
•Converting an expression of a given type into another type is known as
type-casting.
short a=2000;
int b;
b = (int) a; // c-like
or
b = int (a); //c++
Example1:
char z=‘A’;
cout<<z; // print A
int b=int (z);//A=65 in Ascii code
cout<<b; //print 65
or
int b=int(‘A’);//x=65
int x = (int) 89.99; //x = 89
ASCII Character Set:
Each of the 128 values of the ASCII character set represents a
different character.
The value 65 represents 'A', and the value 43 represents '+'.
The value representing 'B' is 66, so 'A' is smaller than 'B'.
'+' is smaller than 'A' since 43 is smaller than 65.
The 14th character in the set is the new line character.
In C++, the new line character is represented as '\n'.
The null character is represented as '\0'.
ASCII (American Standard Code for Information Interchange)
0
1
2
3
4
5
6
7
8
9
0 nul soh stx etx eot enq
ack bel bs
ht
1 lf
vt
ff
cr
so
si
del dc1 dc2 dc3
2 dc4 nak syn etb can em
sub esc fs
gs
3 rs
us
b
!
“
#
$
%
&
‘
4 (
)
*
+
,
.
/
0
1
5 2
3
4
5
6
7
8
9
:
;
6 <
=
>
?
@
A
B
C
D
E
7 F
G
H
I
J
K
L
M
N
O
8 P
Q
R
S
T
U
V
W
X
Y
9 Z
[
\
]
^
_
`
a
b
c
10 d
e
f
g
h
i
j
k
l
m
11 n
o
p
q
r
s
t
u
v
w
12 x
y
z
{
|
}
~
del