# Chapter 4 Looping Structures¶

## Example 4.1 , Page No.88¶

In [1]:
x=0
print "The value of x is ",x
x+=1
print "The value of x is ",x

The value of x is  0
The value of x is  1


## Example 4.2, Page No.89¶

In [3]:
x=0
y=0
print "The value of y is ", y+1
print "The value of x is ", x+1

The value of y is  1
The value of x is  1


## Example 4.3, Page No.89¶

In [5]:
x=0
y=1
x=(y)*2
print "The Value of x ",x
x=0
y=1
x=(y+1)*2
print "The Value of x ",x

The Value of x  2
The Value of x  4


## Example 4.4, Page No.90¶

In [6]:
x=0
y=0
x=(y)*4
print "The Value of x", x
y=0
x=(y+1)*4
print "The Value of x", x

The Value of x 0
The Value of x 4


## Example 4.5, Page No.92¶

In [7]:
x=1
y=1
x=(y)*4
print "The value of x is ",x
y=1
x=(y-1)*4
print "The value of x is ",x

The value of x is  4
The value of x is  0


## Example 4.6, Page No. 93¶

In [8]:
x=1
y=2
x=y*x+1
print "The value of x is: ",x
x=1
y=2
x+=y*x+1
print "The value of x is: ",x

The value of x is:  3
The value of x is:  4


## Example 4.7, Page No.94¶

In [9]:
x=1
y=2
x=y*x+1
print "The value of x is: ",x
x=1
y=2
x-=y*x+1
print "The value of x is: ",x

The value of x is:  3
The value of x is:  -2


## Example 4.8, Page No.95¶

In [11]:
x=0
while (x<10):
print "The value of x is ",x
x=x+1

The value of x is  0
The value of x is  1
The value of x is  2
The value of x is  3
The value of x is  4
The value of x is  5
The value of x is  6
The value of x is  7
The value of x is  8
The value of x is  9


## Example 4.9, Page No.97¶

In [13]:
iSelection=0
while (iSelection!=4):
print "1\tDeposit Funds"
print "2\tWithdraw Funds"
print "3\tPrint Balance"
print "4\tQuit"
print "Thank you"

1	Deposit Funds
2	Withdraw Funds
3	Print Balance
4	Quit
1	Deposit Funds
2	Withdraw Funds
3	Print Balance
4	Quit
Thank you


## Example 4.10, Page No.99¶

In [1]:
x=9
while (x<10):
print "This printf statement is executed at least once"
x=x+1
while (x<10):
print "This printf statement is never executed "
x=x+1

This printf statement is executed at least once


## Example 4.11, Page No.100¶

In [2]:
for x in range(10,5,-1):
print "The value of x is ",x

The value of x is  10
The value of x is  9
The value of x is  8
The value of x is  7
The value of x is  6


## Example 4.12, Page No.101¶

In [2]:
import random
iNumQuestions=int(raw_input("Enter the number of questions to ask: "))
for x in range(iNumQuestions):
iRndNum1=(random.randint(0,100)%10)+1
iRndNum2=(random.randint(0,100)%10)+1
iResponse=int(raw_input("what is "+ str(iRndNum1)+" * "+str(iRndNum2)+" : "))
if(iResponse==(iRndNum1*iRndNum2)):
print "Correct"
else:
print "The Corrent answer was ", iRndNum1*iRndNum2

Enter the number of questions to ask: 2
what is 6 * 9 : 54
Correct
what is 8 * 5 : 32


## Example 4.13, Page No.102¶

In [3]:
for x in range(10,5,-1):
if x==7:
break
print x

7


## Example 4.14, Page No.103¶

In [4]:
for x in range(10,5,-1):
if x==7:
continue
print x

10
9
8
6


## Example 4.15, Page No.104¶

In [6]:
for x in range(25):
print "\n"





## Example 4.16, Page No. 106¶

In [1]:
import time
import random
import os
cYesNo=raw_input("Play a game of Concentration?(y or n)")
if(cYesNo=='y' or cYesNo=='Y'):
i1=random.randint(0,100) % 100
i2=random.randint(0,100) % 100
i3=random.randint(0,100) % 100
print "Concentrate on the next three numbers\n",i1,i2,i3
iCurrentTime=int(round(time.time()*1000))
iElapsedTime=int(round(time.time()*1000))
while((iCurrentTime-iElapsedTime)<3):
iElapsedTime=int(round(time.time()*1000))
os.system('cls')
iResp1=int(raw_input("Enter a number:"))
iResp2=int(raw_input("Enter a number:"))
iResp3=int(raw_input("Enter a number:"))

if(i1==iResp1 and i2==iResp2 and i3==iResp3):
print "Congratulations!"
else:
print "Sorry, Correct numbers were ",i1,i2,i3

Play a game of Concentration?(y or n)n