C programming Tutorial Session 2

OBJECTIVES
• Discuss variables
•Differentiate between variables and constants
•List the different data types and make use of them
in C programs
• Discuss arithmetic operators
Presented by: Muhammad Ehtisham Siddiqui (BSCS)
2

VARIABLE
3

VARIABLE EXAMPLE
• BEGIN
• DISPlAY ‘Enter 2 numbers’
• INPUT A, B
• C = A + B
• DISPLAY C
• END
A, B and C are variables in the pseudocode
BEGIN DISPlAY ‘Enter 2 numbers’ INPUT A, B C = A + B DISPLAY C END
Variable names takes away the need for a programmer to access memory locations using their address
The operating system takes care of allocating space for the variables
4

CONSTANT
• A constant is a value whose worth never changes.
• Example:
• 5 numeric / integer constant
• 5.3 numeric / float constant
• ‘Black’ string constant
• ‘C’ Character constant
• Variable holds constant values
• Int a=5;
• Char a=‘C’
5

IDENTIFIERS
• The names of variables, functions, labels, and various other user defined objects are
called identifiers
• Some correct identifier names
• arena
• s_count
• marks40
• class_one
• Some In correct identifier names
• 1sttest
• oh!god
• start...end
6

IDENTIFIERS
• Identifiers can be of any convenient length, but the number of characters in a
variable that are recognized by a compiler varies from compiler to compiler
• Identifiers in C are case sensitive
7

KEYWORD
All languages reserve certain words for their
internal use
Keywords hold a special meaning within the
context of the particular language
No problem of conflict as long as the keyword
and the variable name can be distinguished.
For example, having integer as a variable name
is perfectly valid even though it contains the
keyword int
8

DATA TYPES
9
o data type or
simply type is a
classification of data which
tells
the compiler or interpreter
how the programmer
intends to use the data.
o A data type provides a set
of values from which
an expression (i.e. variable,
function...) may take its
values.

INT DATA TYPE
• Stores numeric data
• int num;
• Cannot then store any other type of data like “Alan” or “abc”
• 16 bits (2 bytes)
• Integers in the range -32768 to 32767
•
• Examples:
• 12322,
• 0,
• -232
10
#include<stdio.h>
void main()
{
Int i=98;
Int j=-67;
}

FLOAT
Stores values containing decimal places
float num;
 Precision of upto 6 digits
32 bits (4 bytes) of memory
Examples:
23.05,
 56.5,
 32
11
#include<stdio.h>
void main()
{
Float var=
28.00006;
}

DOUBLE
• Stores values containing decimal places
• double num;
• Precision of upto 10 digits
• 64 bits (8 bytes) of memory
• Examples: ‘a’, ‘m’, ‘$’ ‘%’ , ‘1’, ’5’
12
#include<stdio.h>
void main()
{
DOUBLE var=
’28%’;
}

CHAR
• Stores a single character of information
• char gender; gender='M';
• 8 bits (1 byte) of memory
• Examples: ‘a’, ‘m’, ‘$’ ‘%’ , ‘1’, ’5’
13
#include<stdio.h>
void main()
{
Char var= ’X’;
}

VOID
• Stores nothing
• Indicates the compiler that there is nothing to expect
14

RANGE
15

DECLARING VARIABLE
main ()
{
char abc; /*abc of type character */
int xyz; /*xyz of type integer */
float length; /*length of type float */
double area; /*area of type double */
long liteyrs; /*liteyrs of type long int */
short arm; /*arm of type short integer*/ }
16

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C programming Tutorial Session 2

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