PROGRAMMING FUNDAMENTALS
Lab Manual
SESSION: 2022
SEMESTER: 1ST
Course Code: CC1021L
LAB 02: Variables, Datatypes and Operators
CLO 2
Objective(s):
1. Using standard datatypes in C++
2. Declaring and Initialization of Variables
3. Declaring and Defining Constants
4. Use of Arithmetic Operators
5. Use of manipulator functions
Data types:
Data types portray the amount of memory to be allocated. Most common data types are
integer, floating- point, character, strings, bool.
Built – In Data Types in C++
DATA TYPE
bool
MEMORY
(BYTES)
1
char
unsigned char
short
unsigned short
int
unsigned int
long
unsigned long
float
double
long double
1
1
2
2
2
2
4
4
4
8
10
MINIMUM
VALUE
Logical Value
true/false
-128
0
-32768
0
-32768
0
-2147483648
0
10-38
10-308
104932
MAXIMUM
VALUE
Logical Value
true/false
127
255
32767
65535
32767
65535
2147483647
4294967295
1038
10308
104932
Declaration of Variables
Declaration of variables means that compiler assigns a memory location for the
variable. Declaration of a variable consists of data type and the variable name.
Data type var_name;
e.g: int var,number;
float num sum;
char ch;
Initialization of variables
Initialization of variables assigns an initial value to the variable declared. Variable value
is initialized by giving variable a name consisting of equal sign followed by a constant
value.
Data type var_name=value;
e.g: int num=5;
float num=4.5, sum=0;
char ch=’A’;
Example :
// This program has variables of several of the integer types.
#include <iostream>
using namespace std;
int main()
{
int checking;
unsigned int miles;
long days;
checking = -20;
miles = 4276;
days = 189000;
cout << "We have made a long journey of " << miles;
cout << " miles.\n";
cout << "Our checking account balance is " << checking;
cout << "\nAbout " << days << " days ago Columbus ";
cout << "stood on this spot.\n";
return 0;
}
Program Output:
We have made a long journey of 4276 miles.
Our checking account balance is -20
About 189000 days ago Columbus stood on this spot.
OPERATORS
Operators are in C++ to perform operations on variables and constants. Operators in C++ are:
• Arithmetic Operators
• Relation Operators
• Logical Operators
•
Assignment Operators
•
Compound Operators
1) Arithmetic Operator
Basic arithmetic operators in C++ are: *, /, -, +, ++, -- are the arithmetic operators.
Example
Suppose X and Y are two variables with X=5, Y=10
OPERATORS
DESCRIPTION
EXAMPLE
+
Adds both operands
X + Y = 15
Subtracts both operands
Y-X=5
*
Multiply both operands
X * Y = 150
/
Divide both operands
Y/X=2
%
Y/X=0
Remainder after division of
numbers
++
Increase operator by 1
X++ = 6
-Decrease operator by 1
Y-- = 9
2) Relational Operators
Relational Operators perform comparison between the variables. It gives
Boolean values, if the condition is fulfilled it becomes true otherwise false.
Example
Suppose A=5 and B=10.
OPERATORS
>
<
>=
<=
!=
==
DESCRIPTION
EXAMPLE
Checks which operand is
(A>B) False
greater than the other.
(B>A) True
Checks which operand is
(A<B) True
smaller.
(A<B) False
Checks whether the operand is (A>=B) False
greater than or equal to the other (B>=A) True
operand.
Checks whether the operand is (A<=B) True
smaller than or equal to the other (B>=A) False
operand.
Checks whether both the
operands are not equal.
Checks whether both the
operands values is equal.
(A!=B) True
(A==B) False
3) Logical Operators
Logical operators check whether the condition is true or false.
Example:
Suppose if X=10 and Y=5
OPERATORS
DESCRIPTION
EXAMPLE
AND
(X==10 && Y==5) TRUE
TRUE: If both the conditions
are true.
||
True: If only one condition is
true.
(X==10 && Y==8) TRUE
!
It reverses the state of its
operand.
!(X==Y) TRUE
4) Assignment Operators
The assignment operator is used to assign a value to a variable. x=5. It means, 5 is
assigned to variable to x. x=y; It means, the value of y is assigned to x.
5) Compound Operators
They modify the variable by performing an operation on it.
Example:
#include <iostream>
using namespace std;
void main(){
int a=0,b=1,c=2,d=4,e=8;
a+=2;
cout<<"Value of a is "<<a;
b-=8;
cout<<"Value of b is "<<b;
c*=4;
cout<<"Value of c is "<<c;
d/=2;
cout<<"Value of d is "<<d;
e%=4;
cout<<"Value of e is "<<e;
}
Output:
Value of a is 2
Value of b is -7
Value of c is 8
Value of d is 2
Value of e is 0
NAMED CONSTANT
A named constant is like a variable, but its content is read-only, and cannot be changed
while the program is running. Here is a definition of a named constant:
const double INTEREST_RATE = 0.129;
It looks just like a regular variable definition except that the word const appears before the
data type name, and the name of the variable is written in all uppercase characters. The key
word const is a qualifier that tells the compiler to make the variable read-only. Its value
will remain constant throughout the program’s execution. It is not required that the variable
name be written in all uppercase characters, but many programmers prefer to write them
this way so they are easily distinguishable from regular variable names.
Example:
// This program calculates the area of a circle.
// The formula for the area of a circle is PI times
// The radius squared. PI is 3.14159.
#include <iostream>
#include <math.h> // needed for pow function
(See Book Page 127 for more information)
using namespace std;
int main()
{
const double PI = 3.14159;
double area, radius;
cout << "This program calculates the area of a circle.\n";
cout << "What is the radius of the circle? ";
cin >> radius;
area = PI * pow(radius, 2.0);
cout << "The area is " << area << endl;
return 0;
}
Output:
This program calculates the area of a circle.
What is the radius of the circle? 2
The area is 12.56