how to declare variables

1. Python Programming
Unit – I (Part II)
(Lecture 4)
Variables,
Assignment
Statements

2. Lecture 4
Assignment
statements
Comments
Key Words
Order of
Operations
Script Mode
String Operations
Variables, Assignment Statements
Lecture 5

3. Lecture 4
Assignment
statements
Key Words
Script Mode
Variables, Assignment Statements

4. if
import
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is
lambda
Nonlocal
with
yield
except
finally
for
from
global
raise
try
while
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continue
def
del
elif
pass
else
return
and
as
assert
async
await
break
not
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35
key
words
Started
with
capitals
True
False
None
Key Words

5. Lecture 4
Assignment
statements
Key Words
Script Mode
Variables, Assignment Statements

6. Assignment statements
• A variable is a quantity that may change
within the context of a mathematical
problem or expression.
• In python a variable is created by assign
a value to it.

7. Assignment statements
a = 10
b = 20
c = a + b
word = “hello”
num = 20
num = 10
NUM = 20
nUM = 30
Num = 40
All are different

8. • Use letters
• Use numbers
with letters
• Use ‘_’ for
long names
Assignment statements
a = 5  a variable
A = 6  a variable
(note : A & a are different variables)
A 1 = 10  a variable
my_name = “Raja”  a variable

9. • Don’t start
with number
• Don’t use
keywords as
variable
names
Assignment statements
2a = 100  syntax error
a2 = 100  is a variable
if = 5  is a syntax error
If = 5  If is a variable
True = 6  is a syntax error
true = 6  true is a variable

10. Lecture 4
Assignment
statements
Key Words
Script Mode
Variables, Assignment Statements

11. • Contains a
sequence of
statements
• Results appear
one at a time
Script Mode

12. Lecture 4
Assignment
statements
Key Words
Script Mode
Variables, Assignment Statements

13. Python Programming
Unit – I (Part II)
(Lecture 5)
Variables,
Assignment
Statements

14. Lecture 4
Assignment
statements
Comments
Key Words
Order of
Operations
Script Mode
String Operations
Variables, Assignment Statements
Lecture 5

15. Comments
Order of
Operations
String Operations
Variables, Assignment Statements
Lecture 5

16. • An expression is a combination of
values, variables, and operators.
• Consider a=1, b=5, c=6, d=3.
Evaluate b – a * c / d + 10
Order of Operations

17. Rules of precedence

18. Comments
Order of
Operations
String Operations
Variables, Assignment Statements
Lecture 5

19. + is used for
combining
String Operations
“Hello” + “world”  Hello world
a = “welcome”
b = “to”
c = “python”
d = a + b + c  “Welcome to python”

20. * is used for
Repeating
String Operations
“Hi ” * 3  “Hi Hi Hi”
a = “hello ”
b = a*2  “hello hello”

21. Comments
Order of
Operations
String Operations
Variables, Assignment Statements
Lecture 5

22. Comments
a = 10 # a value assigned
b = 20 # b value assigned
c = a + b # sum of a and b assigned to c
# symbol is used to add comments

23. Comments
Order of
Operations
String Operations
Variables, Assignment Statements
Lecture 5

24. Python Programming
Unit – I (Part III)
(Lecture 6)
Functions

25. Lecture 6
Why Functions?
How to use
Functions?
Types of functions
Functions
Types Conversions

26. Why Functions?
Function:
Statement 3
Statement 4
Statement 5
Statement 6
Program:
Statement 1
Statement 2
Statement 3
Statement 4
Statement 5
Statement 6
Statement 7
Statement 3
Statement 4
Statement 5
Statement 6
….
….

27. Why Functions?
Program (without
functions):
Statement 1
Statement 2
Statement 3
Statement 4
Statement 5
Statement 6
Statement 7
Statement 3
Statement 4
Statement 5
Statement 6
….
….
Program (with
functions):
Statement 1
Statement 2
Call function
Statement 7
Call function
….
….

28. Lecture 6
Why Functions?
How to use
Functions?
Types of functions
Functions
Types Conversions

29. Function:
Statement 3
Statement 4
Statement 5
Statement 6
….
….
Program:
Statement 1
Statement 2
Call function
Statement 7
Call function
….
….
Executed
How to use Functions?

30. Lecture 6
Why Functions?
How to use
Functions?
Types of functions
Functions
Types Conversions

31. Types of functions
1. Built-in functions
2. User defined functions

32. Types of functions
1. Built-in functions

33. Types of functions
1. Built-in functions
2. User defined functions

34. Types of functions
2. User defined functions
def function_name (arguments):
statement 1
statement 2
statement 3
…

35. Lecture 6
Why Functions?
How to use
Functions?
Types of functions
Functions
Types Conversions

36. Types Conversions
a = “10” string
int(a) is 10  converted to integer
float(a) is 10.0  converted to float
b = 10.568  float
str(b) is “10.568”  converted to string

37. Lecture 6
Why Functions?
How to use
Functions?
Types of functions
Functions
Types Conversions