Introduction
to fundamental Data types:
Fundamental
(atomic) data types are predefined data types available with C++. There are
five fundamental data types in C++: char,
int, float, double and void.
Actually, these are the keywords for defining the data types.
Integers
are whole numbers without any fraction. Integers can be positive or negative.
Integer data type accepts and returns only integer numbers. If a variable is
declared as an int, C++ compiler
allows storing only integer values into it. If you try to store a fractional
value in an int type variable it will accept only the integer portion of the
fractional value..
//Program to receive two integer numbers and display their sum
#include <iostream>
using namespace std; int main()
{
int num1, num2, sum;
//variables num1, num2, and sum are
declared as integers
cout
<< "\n Enter Number 1: ";
cin >> num1;
cout <<
"\n Enter Number 2: "; cin >> num2;
sum = num1 + num2;
cout <<
"\n The sum of " << num1 << " and " <<
num2 << " is " << sum;
}
In
the above program, there are three variables declared viz. num1, num2 and sum. All
these three variables are declared as integer types. So, three different
integer values can be stored in these variables.
The
variables num1 and num2 are used to store the values that
are obtained from the user during the execution of the program, whereas the
variable sum is used to store the processed (resultant) value.
During the execution of the above program, line numbers 7 and 9 prompt the user to Enter number 1 and number 2.
Input stream cin
in line 8 and 10 will receive the values given by the user and store the same
in variable num1 and num2.
Line
11; both the values of num1 and num2 will be added and the result will
be assigned to the variable sum.
Character
data type accepts and returns all valid ASCII characters. Character data type
is often said to be an integer type, since all the characters are represented
in memory by their associated ASCII
Codes. If a variable is declared as char, C++ allows storing either a
character or an integer value.
#include <iostream>
using namespace std;
int main()
{
char ch;
cout <<
"\n Enter a character: ";
cin >> ch;
ch = ch + 1;
cout <<
"\n The Next character: " << ch;
}
Enter a character: A
The Next character: B
In
the above program, ch is declared as
a char type variable to hold a character. When the user enters a character, it
will be stored in the ch variable as
an integer value (ie. Equivalent ASCII code).
ch = ch + 1;
In
this statement, the value of ch is
incremented by 1 and the new value is stored back in the same variable ch. (Remember that, arithmetic
operations are carried out only on the numbers not with alphabets).
Another
program illustrates how int and char data types are working together.
#include <iostream>
using namespace std;
int main ()
{
int n;
char ch;
cout <<
"\n Enter an ASCII code (0 to 255): ";
cin >> n;
ch = n;
cout <<
"\n Equivalent Character: " << ch;
}
Enter an ASCII code (0 to 255): 100
Equivalent Character: d
In
the above program, variable n is
declared as an int type and another variable ch as a char type. During execution, the program prompts the user
to enter an ASCII value. If the user enters an ASCII value as an integer, it
will be stored in the variable n. In
the statement ch = n; the value of n is assigned into ch. Remember that, ch is
a char type variable.
For
example, if a user enters 100 as input; initially, 100 is stored in the
variable n. In the next statement, the
value of n i.e., 100 is assigned to ch. Since, ch is a char type; it shows the corresponding ASCII character as
output. (Equivalent ASCII Character for 100 is d).
If
a variable is declared as float, all values will be stored as floating point
values.
(1)
They can represent values between the integers.
(2)
They can represent a much greater range of values.
At
the same time, floating point operations takes more time to execute compared to
the integer type ie., floating point operations are slower than integer
operations. This is a disadvantage of floating point operation.
#include <iostream>
using namespace std;
int main()
{
float r, area;
cout <<
"\n Enter Radius: ";
cin >> r;
area = 3.14 * r * r;
cout <<
"\n The Area of the circle is " << area;
}
Enter Radius: 6.5
The Area of the circle is 132.665
In
the above example, two variables r
and area are declared as float type
in a single statement. Variable r is
used to hold radius which is a data provided by the user and area for holding the area of the circle
which is obtained through the formula. For example, if the user inputs the
radius value as 6.5, then the statement area
= 3.14 * r * r; multiplies the value of r twice with 3.14 (value of pi) and the resultant value 132.665
will be kept in the variable area.
In
this case, r and area both are same type of variables.
So, these two variables are declared in a single statement. Declaring the same
variables in a single statement reduces the processing time rather than
multiple declarations.
This
is for double precision floating point numbers. (precision means significant
numbers after decimal point). The double is also used for handling floating
point numbers. But, this type occupies double the space than float type. This
means, more fractions can be accommodated in double than in float type. The
double is larger and slower than type float. double is used in a similar way as
that of float data type.
The
literal meaning for void is ‘empty space’. Here, in C++, the void data type
specifies an empty set of values. It is used as a return type for functions
that do not return any value.
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