Before you keep reading...

Runestone Academy can only continue if we get support from individuals like you. As a student you are well aware of the high cost of textbooks. Our mission is to provide great books to you for free, but we ask that you consider a $10 donation, more if you can or less if $10 is a burden.

Support Runestone Academy Today

Before you keep reading...

Making great stuff takes time and $$. If you appreciate the book you are reading now and want to keep quality materials free for other students please consider a donation to Runestone Academy. We ask that you consider a $10 donation, but if you can give more thats great, if $10 is too much for your budget we would be happy with whatever you can afford as a show of support.

Support Runestone Academy Today

Chapter 9 Exercises

1. Fix 5 errors in code below to correctly print: “Rubber baby buggy bumpers.”

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA Phrase = "Rubber baby buggy bumpers. # STEP 3: LOOP THROUGH THE DATA for letter in phrase # STEP 4: ACCUMULATE newString = newString letter # STEP 5: PROCESS RESULT print(newString

   Change Phrase to phrase and add a " at the end of the line. Add a : at the end of line 6. Add a + in line 8. Add a ) at the end of line 10.

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "Rubber baby buggy bumpers." # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = newString + letter # STEP 5: PROCESS RESULT print(newString)

   Show Comments

2. The code currently prints the reverse of a string. Change it so that it prints the string in the correct order, but every character is separated by a space (there should even be a space between a space and the next character).

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "This is a string." # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString # STEP 5: PROCESS RESULT print(newString)

   In line 3, newString should equal newString + letter + " ". The order does matter.

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "This is a string." # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = newString + letter + " " # STEP 5: PROCESS RESULT print(newString)

   Show Comments

3. Fix the indention on 4 lines below to correctly print the reverse of the string. It should print: “!yadhtriB yppaH.”

   # STEP 1: INITIALIZE ACCUMULATORS newString = "" # STEP 2: GET DATA phrase = "Happy Birthday!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString # STEP 5: PROCESS RESULT print(newString)

   Change the indention on lines 4, 7, 8, and 10 as shown below.

   # STEP 1: INITIALIZE ACCUMULATORS newString = "" # STEP 2: GET DATA phrase = "Happy Birthday!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString # STEP 5: PROCESS RESULT print(newString)

   Show Comments

4. Fix the errors in the code to correctly print the reverse of the string. It should print: “!gnirts a m’I ,kool yeH”

   # STEP 2: GET DATA phrase = "Hey look, I'm a string!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: newString = "" # STEP 4: ACCUMULATE newString = newString + phrase # STEP 5: PROCESS RESULT print(phrase)

   newString should be initialized outside of the for loop. Inside the for loop, it should equal letter + newString and the print statement should be outside the for loop and it should print the newString

   # STEP 1: INITIALIZE ACCUMULATORS newString = "" # STEP 2: GET DATA phrase = "Hey look, I'm a string!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString # STEP 5: PROCESS RESULT print(newString)

   Show Comments

5. Fix 4 errors in the code below to correctly print the mirror of the text in phrase. It should print: “tset a si sihTThis is a test.”

   # STEP 1: INITIALIZE ACCUMULATOR newString = # STEP 2: GET DATA phrase = "This is a test" # STEP 3: LOOP THROUGH THE DATA for l in phrase: # STEP 4: ACCUMULATE newString = letter + newString letter # STEP 5: PROCESS RESULT print()

   Initialize newString to the empty string in line 2. Change l to letter in line 6. Add a + in line 8. Add newString on line 10.

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "This is a test" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString + letter # STEP 5: PROCESS RESULT print(newString)

   Show Comments

6. The code currently prints each letter of the string twice in a row. Change it so that it prints the mirror of the string. It should print: “!rorrim a ni gnikool ekil s’tIIt’s like looking in a mirror!”

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "It's like looking in a mirror!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = newString + letter + letter # STEP 5: PROCESS RESULT print(newString)

   Change line 4 to be newString = letter + newString + newString

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "It's like looking in a mirror!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString + letter # STEP 5: PROCESS RESULT print(newString)

   Show Comments

7. The code below is supposed to replace all 1’s with i’s, but it is in an infinite loop. You can reload the page to stop the infinite loop. Add a line to make the code work. It should print: “This is a string.”

   str = "Th1s is a str1ng" pos = str.find("1") while pos >= 0: str = str[0:pos] + "i" + str[pos+1:len(str)] print(str)

   Add line 5 as shown below.

   str = "Th1s is a str1ng" pos = str.find("1") while pos >= 0: str = str[0:pos] + "i" + str[pos+1:len(str)] pos = str.find("1") print(str)

   Show Comments

8. Fix the errors so that the code prints “I’m just a string.”

   # STEP 1: INITIALIZE ACCUMULATOR newString = " " # STEP 2: GET DATA phrase = "I'm just a string." # STEP 3: LOOP THROUGH THE DATA for phrase in letter # STEP 4: ACCUMULATE letter = letter + newString # STEP 5: PROCESS RESULT print(newString)

   newString should not be initialized with spaces. On line 3, it should be “for letter in phrase:”. Line 4 should be “newString = newString + letter”.

   # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "I'm just a string." # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = newString + letter # STEP 5: PROCESS RESULT print(newString)

   Show Comments

9. The program below is supposed to encode the text in message, but it has 5 errors. Fix the errors so that it prints: “nvvg.nv.zg.nrwmrtsg.”

   message = "meet me at midnight" str = "abcdefghijklmnopqrstuvwxyz. eStr = zyxwvutsrqponmlkjihgfedcba ." encodedMessage = message for letter in message pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] print encodedMessage)

   Change line 2 to end in ". Change line 3 to start the string with ". Change line 4 to set encodeMesage to the empty string to start. Add : at the end of line 5. Add ( on line 8.

   message = "meet me at midnight" str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." encodedMessage = "" for letter in message: pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] print(encodedMessage)

   Show Comments

10. The code currently prints “This is a striniThis is a string”. Fix the error so that it replaces every “1” with “i” and prints “This is a string”.

    str = "Th1s is a str1ng" pos = str.find("1") while pos >= 0: pos = str.find("1") str = str[0:pos] + "i" + str[pos+1:len(str)] print(str)

    At the end of the body of the while loop, make sure to find the “1” again.

    str = "Th1s is a str1ng" pos = str.find("1") while pos >= 0: str = str[0:pos] + "i" + str[pos+1:len(str)] pos = str.find("1") print(str)

    Show Comments

11. Rewrite the following code to create a function that takes a string and returns the reverse of the string. It should print: “!yadhtriB yppaH.”

    # STEP 1: INITIALIZE ACCUMULATORS newString = "" # STEP 2: GET DATA phrase = "Happy Birthday!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString # STEP 5: PROCESS RESULT print(newString)

    Define the function as shown below. Call the function and print the result.

    def reverse(phrase): # STEP 1: INITIALIZE ACCUMULATORS newString = "" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString # STEP 5: PROCESS RESULT return(newString) print(reverse("Happy Birthday!"))

    Show Comments

12. Fix the errors in the code so that it replaces the misspelled word “recieved” with the correct spelling “received”

    str = "He recieved candy" pos = str.find("received") while pos >= 0: str = str[0:pos+len("recieved")] + "received" + str[pos:len(str)] pos = str.find("recieved") print(str)

    In line 2, make sure to find the position of the misspelled word. In line 4, str = str[0:pos] + "received" + str[pos+len("recieved"):len(str)].

    str = "He recieved candy" pos = str.find("recieved") while pos >= 0: str = str[0:pos] + "received" + str[pos+len("recieved"):len(str)] pos = str.find("recieved") print(str)

    Show Comments

13. Rewrite the following code to create a function that takes a string and returns the mirror of the string. It should print: “!ssalC iHHi Class!”.

    # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 2: GET DATA phrase = "This is a test" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString + letter # STEP 5: PROCESS RESULT print(newString)

    Define the function as shown below. Call the function and print the result.

    def mirror(phrase): # STEP 1: INITIALIZE ACCUMULATOR newString = "" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString + letter # STEP 5: PROCESS RESULT return(newString) print(mirror("Hi Class!"))

    Show Comments

14. Complete the code to change all the periods to commas.

    str = "I like to eat. sleep. learn. and code!" pos = str. while pos >= : str = str[0:pos] + + str[ :len(str)] pos = print(str)

    On line 2, use the find method to find the period. On line 3, pos should be greater than or equal to 0. Line 4 should be “str = str[0:pos] + “,” + str[pos+len(“.”):len(str)]” and line 5 should find the next period.

    str = "I like to eat. sleep. learn. and code!" pos = str.find(".") while pos >= 0: str = str[0:pos] + "," + str[pos+len("."):len(str)] pos = str.find(".") print(str)

    Show Comments

15. Modify the code below to create a function that will that will take a message and return an encoded message. It should print: “nvvg.nv.zg.nrwmrtsg.”

    message = "meet me at midnight" str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." encodedMessage = "" for letter in message: pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] print(encodedMessage)

    Define the function as shown below and be sure to return the encoded string. Call the function and print the result.

    def encode(message): str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." encodedMessage = "" for letter in message: pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] return(encodedMessage) print(encode("The password is touchdown."))

    Show Comments

16. Rewrite and fix the errors in the code to be a procedure that takes in a string and prints the reverse of the string and the mirror of the string. Make sure to call the procedure.

    # STEP 1: INITIALIZE ACCUMULATOR reverseString = "" mirrorString = " " # STEP 2: GET DATA phrase = "This is the string" # STEP 3: LOOP THROUGH THE DATA for phrase in phrase: # STEP 4: ACCUMULATE reverseString = reverseString + letter mirrorString = letter + letter + reverseString # STEP 5: PROCESS RESULT print(reverseString) print(mirrorString)

    mirrorString in line 2 should not be set equal to a string of a space. The for loop should be “for letter in phrase”. reverseString should equal letter + reverseString and mirrorString should equal letter + mirrorString + letter.

    def aProcedure(phrase): # STEP 1: INITIALIZE ACCUMULATOR reverseString = "" mirrorString = "" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE reverseString = letter + reverseString mirrorString = letter + reverseString + letter # STEP 5: PROCESS RESULT print(reverseString) print(mirrorString) phrase = "This is the string" aProcedure(phrase)

    Show Comments

17. Modify the code below to create a function that returns the decoded input string. It should print: “meet me at midnight.”

    message = "" str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." encodedMessage = "nvvg.nv.zg.nrwmrtsg" for letter in encodedMessage: pos = eStr.find(letter) message = message + str[pos:pos+1] print(message)

    Define the function as shown below. Be sure to return the decoded message. Call the function and print the result.

    def decode(eMessage): message = "" str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." for letter in eMessage: pos = eStr.find(letter) message = message + str[pos:pos+1] return(message) print(decode("nvvg.nv.zg.nrwmrtsg"))

    Show Comments

18. Finish the code so that it prints the mirror of the string with the correct way then the reverse. It should print: “This is a mirror!!rorrim a si sihT”

    # STEP 1: INITIALIZE ACCUMULATOR newString = "" aString = "" # STEP 2: GET DATA phrase = "This is a mirror!"

    # STEP 1: INITIALIZE ACCUMULATOR newString = "" aString = "" # STEP 2: GET DATA phrase = "This is a mirror!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newString = letter + newString for letter in newString: aString = letter + aString + letter # STEP 5: PROCESS RESULT print(aString)

    Show Comments

19. Create another function that encodes a string. Pass in both the string to be encoded and the string to use to encode the string as well.

    Create a function similar to the encode function above, but change it to take two input values.

    def encode2(message, eStr): str = "abcdefghijklmnopqrstuvwxyz. " encodedMessage = "" for letter in message: pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] return(encodedMessage) print(encode2("This is a test", "zyxwvutsrqponmlkjihgfedcba ."))

    Show Comments

20. Here’s the code to encode a message. Write code underneath it to decode the encoded message and print it.

    message = "meet me at midnight" str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." encodedMessage = "" for letter in message: pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] print(encodedMessage)

    Initialize decodedMessage and then iterate through encodedMessage and in the body of the for loop, just switch eStr and str from the encoded message.

    message = "meet me at midnight" str = "abcdefghijklmnopqrstuvwxyz. " eStr = "zyxwvutsrqponmlkjihgfedcba ." encodedMessage = "" for letter in message: pos = str.find(letter) encodedMessage = encodedMessage + eStr[pos:pos+1] print(encodedMessage) decodedMessage = "" for letter in encodedMessage: pos = eStr.find(letter) decodedMessage = decodedMessage + str[pos:pos+1] print(decodedMessage)

    Show Comments

You have attempted of activities on this page