Class 8 – Friday, September 11

I know that or now I know that, that is the question

We are humankind — What a mantra that could be — I'm human and kind

A name is needed — For our class's string mascot — Have you an idea?

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Look both ways

• Back or ahead

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Request

• One of our course members is in need of a notetaker. Please consider doing so.

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What I want to accomplish today

• Provide experience with string manipulation.

• Reinforce that strings are immutable — there is no Python function to change an existing string.

• Continue gentle introduction to looping.

• Expand our problem solving skills and abilities.

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Downloads

• Program prowess.py

 

• Program case_by_case.py

• Program countability.py

• Program find_the_spot.py

• Program replacement.py

• Program slice_of_pie.py

 

• Program kinda_stringy.py

• Program again_and_again.py

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To do list

• Review class artifacts

• Homework

• Check out my documentation on Python random capabilities

• Check out my epistle on Python list capabilities

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Problem solving — program prowess.py

• Practices some string manipulation. The program task is to

• Prompt and get a line of text.

• Determine and print the length of the text.

• Determine and print the index of last character in the text.

• Determine and print the last character of the text.

• Prints its results.

Two possible program runs

Enter text: Hoos got your back

Input length: 18

Index of last input character: 17

Last character in text: k

Enter text: Enter text: And the winner is ...

Input length: 21

Index of last input character: 20

Last input character: .

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Program case_by_case.py

• Introduces string case functions capitalize(), lower(), and upper()

A possible program run

Enter text: thanks VERY mucH.

text: thanks VERY mucH.

text.lower(): thanks very much. # all lower case

text.upper(): THANKS VERY MUCH. # all upper case

text.capitalize(): Thanks very much. # initial character capitalized, rest lower case

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Program countability.py

• Introduces string function count()

A possible program run

Enter text: any bananas

Enter substring: an

Enter index: 7

text.count( substring ): 3 # count all

text.count( substring, 7 ): 1 # count starting from index 7

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Program find_the_spot.py

• Introduces string member function find()

A possible program run

Enter text: aardvark

Enter substring: a

text.find( substring ): 0 # first occurrence

text.find( substring, 1 ): 1 # second occurrence

text.find( substring, 2 ): 5 # third occurrence

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Program replacement.py

• Introduces string function replace()

A possible program run

Enter text: yellow bellied sapsucker

Enter substring (s): ll

Enter substring (r): L L

text.replace( s, r ): yeL Low beL Lied sapsucker # text's s's replaced with r's

Enter text: yellow bellied sapsucker

Enter substring (s): e

Enter substring (r):

text.replace( s, r ): yllow bllid sapsuckr # text's s's replaced with r's

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Program slice_of_pie.py

• Introduces the sequence slicing operator :

Two possible program runs

Enter favorite pie: anchovies and garlic

Enter two indices: 3 15

s: anchovies and garlic

i: 3

j: 15

s[ i ]: h

s[ j ]: a

s[ i : j ]: hovies and g

s[ i : ]: hovies and garlic

s[ : j ]: anchovies and g

s[ : ]: anchovies and garlic

Enter favorite pie: strawberry rhubarb

Enter two indices: 12 14

s: strawberry rhubarb

i: 12

j: 14

s[ i ]: h

s[ j ]: b

s[ i : j ]: hu

s[ i : ]: hubarb

s[ : j ]: strawberry rhu

s[ : ]: strawberry rhubarb

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Program kinda_stringy.py

• Prints out the characters of two user-supplied strings, character by character. The first without a loop, the second with a loop.

Two possible program runs

Enter a three-letter string: abc

a

b

c

Enter a string: four score

f

o

u

r

s

c

o

r

e

Enter a three-letter string: def

d

e

f

Enter a string: and seven years

a

n

d

f

o

u

r

y

e

a

r

s

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Program again_and_again.py

• Prints requested text requested number of times

Two possible program runs

Enter string to be printed: one more time

Enter number of times to be printed: 3

one more time

one more time

one more time

Enter string to be printed: I said how are you today

Enter number of times to be printed: 5

I said how are you today

I said how are you today

I said how are you today

I said how are you today

I said how are you today

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Program shifty.py

• The program prompts for three strings and prints them in shifted order.

• That is, the third word is printed first, the first word is printed second, and the second word is printed last. This tyype of shifting is called a right circular shift. The printing of the words should be on a single line.

• The solution is not allowed to modify any existing statement.

Two possible program runs

Enter three strings: a b c

Before the shift w1, w2, and w3 are respectively: a b c

After the shift w1, w2, and w3 are respectively: c a b

Enter three strings: kiwi cucumber nectarine

Before the shift w1, w2, and w3 are respectively: kiwi cucumber nectarine

After the shift w1, w2, and w3 are respectively: nectarine kiwi cucumber

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© 2020 Jim Cohoon

Resources from previous semesters are available.