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1 # & for while while # * # & *, /01* for * 2 for <var> in <sequence>: <body>,var 0 2, /01* *** 0 *0 *& 4 00 *0* *

2 /01* 4 6, 4 * /01* Input the count of the numbers, n Initialize sum to 0 Loop n times Input a number, x Add x to sum Output average as sum/n 5 /01* # average1py # A program to average a set of numbers # Illustrates counted loop with accumulator def main: n = inputhow many numbers do you have? sum = 00 for i in rangen: x = inputenter a number >> sum = sum x print \nthe average of the numbers is, sum / n 8&99sum/n 6 /01* How many numbers do you have? 5 Enter a number >> 2 Enter a number >> 45 Enter a number >> 4 Enter a number >> 76 Enter a number >> 45 The average of the numbers is # 0** * 4** 0 * for * 4 * 0* 4 0** * 46 0

$sum = 00 for i in rangen: x = inputenter a number >> sum = sum x print \nthe average of the numbers is, sum / n 8&99sum/n 6 /01* How many numbers do you have?$

3 while <condition>: <body> condition,#0 if 2, 4 0* *, :,while 99 i = 0 while i <= 10: print i i = i 1 for for i in range11: print i while 2 i & 9 for while * ; i = 0 while i <= 10: print i 4*< 4 i 29*9, 9 8* i 9, 5

4 4 < *0 *0 6 * * 1**** 00* < count set moredata to yes while moredata is yes get the next data item process the item ask user if there is moredata * initialize sum to 00 initialize count to 0 set moredata to yes while moredata is yes input a number, x add x to sum add 1 to count ask user if there is moredata output sum/count # average2py # A program to average a set of numbers # Illustrates interactive loop with two accumulators def main: moredata = yes sum = 00 count = 0 while moredata[0] == y: x = inputenter a number >> sum = sum x count = count 1 moredata = raw_inputdo you have more numbers yes or no? print \nthe average of the numbers is, sum / count =, >?9@A* BCBCBC Enter a number >> 2 Do you have more numbers yes or no? y Enter a number >> 45 Do you have more numbers yes or no? yes Enter a number >> 4 Do you have more numbers yes or no? yup Enter a number >> 76 Do you have more numbers yes or no? y Enter a number >> 45 Do you have more numbers yes or no? nah The average of the numbers is 464

$you have more numbers yes or no? print \nthe average of the numbers is, sum / count =, >?9@A* BCBCBC Enter a number >> 2 Do you have more numbers yes or no?$

5 get the first data item while item is not the sentinel process the item get the next data item *,,* 4* *9 * # averagepy # A program to average a set of numbers # Illustrates sentinel loop using negative input as sentinel def main: sum = 00 count = 0 x = inputenter a number negative to quit >> while x >= 0: sum = sum x count = count 1 x = inputenter a number negative to quit >> print \nthe average of the numbers is, sum / count 5 Enter a number negative to quit >> 2 Enter a number negative to quit >> 45 Enter a number negative to quit >> 4 Enter a number negative to quit >> 76 Enter a number negative to quit >> 45 Enter a number negative to quit >> 1 The average of the numbers is 464 * * * 7 9

$inputenter a number negative to quit >> print \nthe average of the numbers is, sum / count 5 Enter a number negative to quit >> 2 Enter a number negative to quit >> 45 Enter a$

6 4 D* = 4 > A6 initialize sum to 00 initialize count to 0 input data item as a string, xstr while xstr is not empty convert xstr to a number, x add x to sum add 1 to count input next data item as a string, xstr Output sum / count # average4py # A program to average a set of numbers # Illustrates sentinel loop using empty string as sentinel def main: sum = 00 count = 0 xstr = raw_inputenter a number <Enter> to quit >> while xstr = : x = evalxstr sum = sum x count = count 1 xstr = raw_inputenter a number <Enter> to quit >> print \nthe average of the numbers is, sum / count Enter a number <Enter> to quit >> 4 Enter a number <Enter> to quit >> 2 Enter a number <Enter> to quit >> 0 Enter a number <Enter> to quit >> 25 Enter a number <Enter> to quit >> 44 Enter a number <Enter> to quit >> 227 Enter a number <Enter> to quit >> The average of the numbers is < # average5py # Computes the average of numbers listed in a file def main: filename = raw_inputwhat file are the numbers in? infile = openfilename,r sum = 00 count = 0 for line in infilereadlines: sum = sum evalline count = count 1 print \nthe average of the numbers is, sum / count

$number <Enter> to quit >> while xstr = : x = evalxstr sum = sum x count = count 1 xstr = raw_inputenter a number <Enter> to quit >> print \nthe average of the numbers is, sum / count Enter a number$

7 E 016 4readline, readline BC line = infilereadline while line = #process line line = infilereadline *G0 < H * * readline *BIC 6JBC 5 # average6py # Computes the average of numbers listed in a file def main: filename = raw_inputwhat file are the numbers in? infile = openfilename,r sum = 00 count = 0 line = infilereadline while line = : sum = sum evalline count = count 1 line = infilereadline print \nthe average of the numbers is, sum / count 8 **** if 4 * * >A ** sum = 00 count = 0 line = infilereadline while line = : #update sum and count for values in line line = infilereadline print \nthe average of the numbers is, sum/count 8,* sum count * * * sum 4count 5

$infile = openfilename,r sum = 00 count = 0 line = infilereadline while line = : sum = sum evalline count = count 1 line = infilereadline print \nthe average of the$

8 8 for xstr in stringsplitline,,: sum = sum evalxstr count = count 1 8for line* 8 # average7py # Computes the average of numbers listed in a file # Works with multiple numbers on a line import string def main: filename = raw_inputwhat file are the numbers in? infile = openfilename,r sum = 00 count = 0 line = infilereadline while line = : for xstr in stringsplitline,,: sum = sum evalxstr count = count 1 line = infilereadline print \nthe average of the numbers is, sum / count 8 while for 4, 8 ** * * * if while,,true alse *G, * >while x >= 0A,, **, 2 2 5

$count 1 line = infilereadline print \nthe average of the numbers is, sum / count 8 while for 4, 8 ** * * * if while,,true alse *G, *$

9 if p1getx == p2getx: if p1gety == p2gety: # points are the same else: # points are different else: # points are different G*0**,6 G0 andornot and or *, <expr> and <expr> <expr> or <expr> 7 9 and *,, *, 4 / / /,,* P and Q or *,*, / / or *, or *,G** BC 7

G*0**,6 G0 andornot and or *, <expr> and <expr> <expr> or

10 not, not, 4 0,,, a or not b and c :*< * notandor 2 a or not b and c G& * *and if p1getx == p2getx and p2gety == p1gety: # points are the same else: # points are different * * 5 * 2 :*,< scorea == 15 or scoreb == 15 4,, 4* H0 6 while notscorea == 15 or scoreb == 15: #continue playing 7 9 9

else: # points are different * * 5 * 2 :*,< scorea == 15 or scoreb == 15

11 2 *5 while notscorea == 15 or scoreb == 15 or \ scorea == 7 and scoreb == 0 or scoreb == 7 and scorea == 0: #continue playing 0 * * * * # 9 a >= 15 and a b >= 2 or b >= 15 and b a >= 2 a >= 15 or b >= 15 and absa b >= 2 *, 0, * M9J9 MJ L9J JJ JJ JJ and or 0 1 or* a or true == true and or a or b and c == a or b and a or c a and b or c == a and b or a and c notnot a == a E G* nota or b == not a and not b nota and b == not a or not b 4, while notscorea == 15 or scoreb == 15: #continue playing 0B4 C E G* while not scorea == 15 and not scoreb == 15: #continue playing

and or a or b and c == a or b and a or c a and b or c == a and b or a and c notnot a == a E G* nota or b == not a and not b nota and b == not

12 while scorea = 15 and scoreb = 15 # continue playing G<B4 C * * * not E G* *2, 5 if while, *** repeat get a number from the user until number is >= 0 4 *, * * while 5 5

5 if while, *** 0 7 59 repeat get a number

13 4*, number = 1 while number < 0: number = inputenter a positive number: number ;*, break break, break,* * break while True: number = inputenter a positive number: if x >= 0: break # Exit loop if number is valid *, True *0 06 4, break,* if :6 4G * **< 5 5 while *0* number = 1 while number < 0: number = inputenter a positive number: if number < 0: print The number you entered was not positive 4G 0* 6 * break else while True: number = inputenter a positive number: if x >= 0: break # Exit loop if number is valid else: print The number you entered was not positive 55 5

while number < 0: number = inputenter a positive number: if number < 0: print The number you entered was not positive 4G 0* 6 * break else while

14 : * while True: number = inputenter a positive number: if x >= 0: break # Loop exit print The number you entered was not positive :, ** : * while True: get next data item if the item is the sentinel: break process the item : : break * **,, * 0 * >0 A * while response[0] == y or response[0] == Y: 6H 0 while response[0] == y or Y: 4G*0< bool 9True alse 0== *bool

the sentinel: break process the item 6 57 9 : : break 26 0 0* **,, * 0 * >0 A * while

15 :** > A& alse True >>> bool0 alse >>> bool1 True >>> bool2 True >>> boolhello True >>> bool alse >>> bool[1,2,] True >>> bool[] alse 2 alse *2 0True 0, and, or not,,, *,, *, True *alse 5, and, *0*, **G,,,, *,* 7 79

16 * 0* and *, or*,*, response[0] == y or Y * :G2, response[0] == y or Y or,true?9@2bcbhc* 7 7 ** <Enter> ans ans = raw_inputwhat flavor fo you want [vanilla]: if ans: flavor = ans else: flavor = vanilla #<Enter>ans * * ans = raw_inputwhat flavor fo you want [vanilla]: flavor = ans or vanilla 1* True,* 6 flavor = raw_inputwhat flavor do you want [vanilla]: or vanilla &N0 0 * 6 7 7

ans else: flavor = vanilla #<Enter>ans * * 7 7 46 ans = raw_inputwhat flavor fo you want

Python Programming: An Introduction To Computer Science

Python Programming: An Introduction To Computer Science Chapter 8 Booleans and Control Structures Python Programming, 2/e 1 Objectives æ To understand the concept of Boolean expressions and the bool data