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The following example illustrates the combination of an else statement with a for the statement that searches for prime numbers from 10 through 20.

# !/usr/bin/python

for num in range(10,20):

#to iterate between 10 to 20

for i in range(2,num):

#to iterate on the factors of the number

if num%i == 0:

#to determine the first factor

j=num/i

#to calculate the second factor

print ‘%d equals %d * %d’ % (num,i,j)

break

#to move to the next number, the

#first for

else:

# else part of the loop

print num, ‘is a prime number’

When the above code is executed, it produces the following result :

10 equals 2*5

11 is a prime number

12 equals 2*6

13 is a prime number

14 equals 2*7

15 equals 3*5

16 equals 2*8

17 is a prime number

18 equals 2*9

19 is a prime number

#!/usr/bin/python

for letter in ‘Python’: # First Example

print ‘Current Letter :’, letter

fruits = [‘banana’, ‘apple’, ‘mango’]

for fruit in fruits: # Second Example

print ‘Current fruit :’, fruit

print “Good bye!”

When the above code is executed, it produces following result:

Current Letter : P

Current Letter : y

Current Letter : t

Current Letter : h

Current Letter : o

Current Letter : n

Current fruit : banana

Current fruit : apple

Current fruit : mango

Good bye!

A while loop statement in Python programming language repeatedly executes a target statement as long as a given condition is true.

The syntax of a for loop look is as follows:

for iterating_var in sequence :

statements(s)

It causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating.

if expression:

statement(s)

else:

statement(s)

if expression :

statement(s)

The syntax of a while loop in Python programming language is while expression: 

statement(s) 

Here statement(s) may be a single statement or a block of statements. The condition may be any expression, and true is any nonzero value. The loop iterates while the condition is true. 

When the condition becomes false, program control passes to the line immediately following the loop. In Python, all the statements indented by the same number of character spaces after a programming construct are considered to be part of a single block of code. Python uses indentation as its method of grouping statements.

Example

# !/usr/bin/python

count=0

while (count < 9):

print ‘The count is:’,count

count=count +1

print “Good bye!”

OUTPUT

The count is: 0

The count is: 1

The count is: 2

The count is: 3

The count is: 4

The count is: 5

The count is: 6

The count is: 7

The count is: 8

Good bye!

There may be a situation when you want to check for another condition after a condition resolves to true. In such a situation, you can use the nested if construct. In a nested, if construct, you can have an if…elif…else construct inside another if…elif… else construct. 

Syntax:

The syntax of the nested if…elif…else construct may be:

if expression1:

statement(s)

if expression2:

statement(s)

elif expression3:

statement(s)

else

statement(s)

elif expression4: statement(s) else:

statement(s)

Example:

# !/usr/bin/python if var < 200:

print “Expression value is less than 200”

if var==150:

print “=150”

elif var = =100:

print “=100”

elif var ==50:

print “=50”

elif var < 50 :

print “Expression value is less than 50”

else :

print “Could not find true expression”

The two types of Python else clauses are : 

(i) else in an, if statement 

(ii) else in a loop statement 

The else clause of an if statement is executed when the condition of the if statement results in false. 

The else clause of a loop is executed when the loop is terminating normally i.e. when its test-condition has gone false for a while loop or when the for loop has executed the last value in the sequence.

The ‘break’ statement can be used to terminate the loop.

Answer:

def countPages(num):

total = 0

i = 1

while i<=num:

page_no = str(i)

total + = page_no.count(‘1’)

i+ = l

return total

import math

def sqApprox(num):

i = 0

minsq = 0 # set lower bound

maxsq = math.ceil(num’l’num)

# set upper bound

while i< maxsq :

# set ‘while’ termination condition

if i*i< =num and i>minsq:

# complete inequality condition

minsq = i

if i*i> =num and i<maxsq:

# complete inequality condition

maxsq = i

i+=l

# update i so that ‘while’ will terminate

return (minsq, maxsq)

def addNumbers(start, end):

total = 0

i = start

while start < = end:

total + = start

start + = 1

return total

If…else statements

An else statement can be combined with an if statement. An else statement contains the block of code that executes if the conditional expression in the if statement resolves to 0 or a false value.

The else statement is an optional statement and there could be at most only one else statement following if

Syntax:

The syntax of the if…else statement is :

if expression :

statement(s)

else:

statement(s)

Structures require that the programmer specify one or more conditions to be evaluated or tested by the program, along with a statement or statements to be executed if the condition is determined to be- true, and optionally, other statements to be executed if the condition is determined to be false.

def primeNumbers(num):

primes = [ ]

i = 2

# iterates through range from 2 to

num(inclusive)

while i< =num:

# add ‘while’ condition

k = 2

is Prime = True

# check if prime number

while k<i: # add’while’condition

if i%k==0:

isPrime = False

k+ = l # update k

if isPrime = =True:

primes.append(i)

i+ = l # update i

return primes

sum = 0

n = int (raw_input (“Enter number”)

n1 = n

while (n > 0):

a = n%10

sum = sum + (a * a * a)

n = n/10

if (sum ==n1):

print n, “is an Armstrong number”

else:

print n, “is not an Armstrong number”

x = float (raw_input (“Enter value of x :”)

n = int (raw_input (“Enter value of n :”))

s = 0

for a in range (n + 1) :

s + = x**a

print “Sum of series”, s

def Mersenne (n):

return 2** n-1

def test prime (n):

mid = n/2 + 1

for t in range (2, mid):

if n%t = = 0:

return false

else :

return true

print “20 Mersenne Prime Numbers are :”

for a in range (1,21):

number = Mersenne (a)

prime = test prime (number)

if prime :

print number, “Prime”

else :

print number

All give the same output.

for a in range (3,10,2) :

for b in range (1, a, 2):

print b,

print

grade = input (“Enter the grade percentage”) if grade > = 90 :

print “Grade is A+” if 80 < = grade < 90 : print “Grade is A” elsif 60 < = grade : print

“Grade is A-” else grade < 60 :

print “You are fail”

def primeFactorization(num):

factors = [ ]

lastresult = num

# 1 is a special case

if num == 1:

return [ ]

while True:

if lastresult == 1:

break

c = 2

while True:

if lastresult % c = = 0:

break

c += 1

factors.append(c)

lastresult/= c

return factors

def LCM(nums):

nums.sort()

biggest=nums[-l]

multiplier=1

while sum([(multiplier’|,biggest)%num for num in nums])!=0:

multiplier + = 1

return biggest*multiplier

The output is:

2

The output is :

3

The output is:

4

Gets printed with the code True.

The output is:

a

Gets printed the number 13. 

The syntax for a break statement in Python is as follows : break

# program to print multiples of 13 smaller than 100 for the counter in range (13,100,13) :

print counter

The syntax of a while loop in Python programming language is :

while expression :

statement(s)

When the condition becomes false, program control passes to the line immediately following the loop.

The syntax of a for loop looks as follows: for iterating_var in sequence:

statements(s)

Example: for i in range (4):

print i

output : 0 1 2 3

There may be a situation when you want to check for another condition after a condition resolves to true. In such a situation, you can use the nested if construct. In a nested, if construct, you can have an if…elif…else construct inside another if…elif… else construct

A for loop is à Python statement which repeats a group of statements a specified number of times. You can use any object (such as strings, arrays, lists, tuples, diet and so on) in a for loop in Python.

num = input (“Enter the number”)

while (num > = 1) :

print (“num = “, num)

num – num-1

print (“Finish”)

Value of expression is 100

Goodbye

elif statement : The elif statement allows you to check multiple expressions for truth value and execute a block of code as soon as one of the conditions evaluates to true. Like the else, the elif statement is optional. However, unlike else , for which there can be at most one statement, there can be an arbitrary number of elif statements following an if

The syntax of the if…elif statement is

If expression1 :

statement (s)

elif expression2 :

statement(s)

elif expression3 :

statement(s)

else:

statement(s)

Example

# !/usr/bin/py thon

var=100

if var = = 200 :

print “1-Got a true expression value”

print var

elif var==150:

print “2-Got a true expression value”

print var2

elif var ==100:

print “3-Got a true expression value”

print var

else:

print “4-Got a false expression value”

print var

print “Good bye!”

when the above code is executed, it produces the following output :

3- Got a true expression value

100

Good bye !

N = input (“Number of tossing a coin”) from random import choice

heads = 0

tails = 0

coin = [‘head’, ‘tail’]

for n in range (N) :

toss = choice (coin)

if toss = ‘head’ :

heads = heads + 1

if toss = = ‘tail’ :

tails = tails + 1

print (‘Heads:’, heads)

print (‘Tails:’, tails)

Get printed the code yes.

Gets printed the following code 3.

x = input (“Enter a base number”)

y = input (“Enter a exp. number”)

if y > 0 :

for x in range (y) :

x = x * x

else

for x in range (y) :

x = 1/x * x

print x

# !/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!”

When the above code is executed, it produces the following result:

1- Got a true expression value 100

2- Got a false expression value 0

Good bye!

def fibonacci (num)

if (num = = 0):

return 0

elif (num = = 1):

return 1

else :

return fibonacci (num-1) + fibonacci

(num-2)

cal = input (“Enter the input limit”)

print fibonacci (val)

def piApprox(num):

i = 1

pi = 0

while i<=num:

#set ‘while’ termination condition

pi +=((4/float(2*i-l)n-l)**(i+l))

#compute the ith term of the series

i+=l # update i

return pi

num = int (raw_input(“Enter an integer > 1000 : “))

tnum = num

reverse = 0

while tnum :

digit = tnum %10

tnum = tnum /10

reverse = reverse * 10 + digit

print “Reverse of”, num, “is”, reverse

num = int (raw_input (“Enter an integer:”))

mid = num/2

print “The divisors of”, num, “are:”

for a in range (2, mid +1):

if num %a = = 0:

print a,

else:

print”End”