1. Tejalal Choudhary “Computer Programming” Fundamentals of “C”
Store Data
Operate on Data
Perform I/O
Control the sequence
“Computer Programming”
Fundamentals of “C”
VARIABLES, CONSTANTS & DATA TYPES
Tejalal Choudhary
Department of Computer Science & Engg
SDBCT, Indore

2. Contents Need of variable, constant and data types Character set
Constants
Variables
Data types

3. What is C ? Programming Language Simple and easy to use
Many other languages are based on C
Developed at AT & T’s Bell Laboratories of USA in 1972.
Major parts of OS like Windows, UNIX, Linux is still written in C.
Device driver are written in C
Many mobile devices, consumer devices are based on C
Popular gaming frameworks have been built using C
Closely interact with the hardware devices.
and so on…..

4. Analogy b/w English & C Steps in learning English language:
Steps in learning Programming language:
Alphabets
Words
Sentences
Paragraphs
Alphabets,
Digits, Special Symbols
Constants,
Variables,
Keywords
Instructions
Program

5. Identifier Any user defined name Can be a name of
Variable, array, structure, Union ,Function etc.
Should follow the naming rules of a language
Naming Rules
The first character in the variable name must be an alphabet or underscore.
No commas or blanks are allowed within identifier
No special symbol other than an underscore

6. Constants An entity that doesn’t change Types Integer (10, 20)
Real (10.56)
Character (‘a’, ‘A’)

7. Variables Variable is an entity that may change.
It’s a Named memory location
Each variable has some address
Store constant value
If not initialized constrains garbage value
Can store one value at a time
i.e. x=10
x=20
X –> Variable
10, 20 –> constant

8. Variable A B

9. Data-type variable-name;
Data Types
Define Type for variable
Range(max and min value it can store)
Size(space required to store value)
Data Type
char
short
int
long
float
double
General Syntax for Variable Declaration
Data-type variable-name;
Char ch;

11. Byte Binary digit -> bit(0 or 1) One byte 0/1
One Byte can represent 28 =256 distinct values
0/1

12. Char(1 Byte) Char ch=‘A’; //65 64 +1 26+201 26 20

13. Short(2 Byte)
Short s=519;
=519

14. Short(2 Byte) +1
20 +…….+ 214
512+
1024+
2048+
4096+
8192+
16384=
32767 + 1

15. Negative Numbers (Stored in 2’s complement)
Binary of is same as 32768
When we try to store it becomes
Binary of = 1’s Complement of
Binary of is :
1’s complement +1
2’s complement
Binary of

16. Assigning one type to another
Char ch=‘A’; //65
Short s=ch; 65

17. Assigning one type to another
Short s=300; =
Char ch=s; = 44

18. Lab Assignment 2
WAP which accepts a lower case character from the user and display the corresponding upper case character.(Hint: use <string.h> header file and its functions)
Take length & breadth of rectangle from user. WAP to calculate area of rectangle.