PYTHON PROGRAMMING (2010)

Decision making of Python

· Decision making is one of the important aspects of any programming languages.

· Similarly it goes with the python the various structures are as follows.

Flow diagram

· In this programming language it assumes non-zero and non-null value as true.

· But if it is either zero or null it is assumed as false.

Following are the three decision making statement.

· If statement.

· If else statement.

· Nested if statement.

If statement

· Contains logical expression.

· Utilizes these expressions and converts them into a result after comparison.

Syntax

If expression:

Statement

If flow table

Program

#!/usr/bin/python

var1 = 100

if var1:

print "1 - Got a true expression value"

print var1

var2 = 0

if var2:

print "2 - Got a true expression value"

print var2

print "Good bye!"

Output

1 - Got a true expression value

100

Good bye!

If else statement

· If and else are combined.

· Else provide an option to the if statement.

Syntax

if expression:

statement(s)

else:

statement(s)

If else flow table

Program

#!/usr/bin/python

var1 = 100

if var1:

print "1 - Got a true expression value"

print var1

else:

print "1 - Got a false expression value"

print var1

var2 = 0

if var2:

print "2 - Got a true expression value"

print var2

else:

print "2 - Got a false expression value"

print var2

print "Good bye!".

Output

1 - Got a true expression value

100

2 - Got a false expression value

0

Good bye!

Nested if statement

· It is having various conditions one by one in sequence.

· It’s used to resolve one condition after one.

Syntax

if expression1:

statement(s)

if expression2:

statement(s)

elif expression3:

statement(s)

else

statement(s)

elif expression4:

statement(s)

else:

statement(s).

Program

#!/usr/bin/python

var = 100

if var < 200:

print "Expression value is less than 200"

if var == 150:

print "Which is 150"

elif var == 100:

print "Which is 100"

elif var == 50:

print "Which is 50"

elif var < 50:

print "Expression value is less than 50"

print "Could not find true expression"

print "Good by!".

Output

Expression value is less than 200

Which is 100

Good bye!