Lecture 14 - Exercises

14A - String Methods

1. What do each of the following expressions evaluate to?

   1. "Wow".replace("W", "t").upper()
   2. "banana".find("a")
   3. " O_O ".strip().replace("_", "-")
   4. "banana".count("a")

2. Write a single expression that evaluates to the number of occurrences of the letter “E”, regardless of case, in a string s.

14B - String Comparisons and Ordering

3. Evaluate the following expressions:

   1. "To be or not to be".find("be") == 4
   2. "Boo".replace("o", "O").lower() <= "boo"
   3. "no" in "To be or not to be"
   4. "stark" not in "Tony Stark"
   5. "bat" > "rat"
   6. "tap" < "bear"
   7. "Jam" < "bet"
   8. "STEAM" > "STEP!"

4. What does the following program print?

   def sub_lt(s):
       count = 0
       for i in range(len(s)):
           if s[i:] < s:
               count += 1
       return count
   
   print(sub_lt("branStark"))

Problems

1. Implement the following function, but this time use string methods to do it without a loop:

   def remove_vowels(string):
       """ Return string, but with all vowels removed. Don't count y as a vowel. """

2. Implement the following function, but this time use string methods to do it without a loop:

   def remove_comments(string):
       """ Return a copy of string, but with all characters starting with and following
           the first instance of ‘#’ removed. If there is no # in the string, return
           the input unchanged."""

3. Implement the following function:

   def uun_letters(first_name, last_name):
       """ Return the letters in a student's WWU Universal
       Username given the student's first_name and last_name.
       The username begins with the first 6 characters of
       the last name, followed by the first letter of the
       first name. Return the username in all lower case.
       Example: uun_letters("Scott", "Wehrwein") => "wehrwes" """

4. Implement the following function:

   def capitalize_words(string):
       """ Return a copy of string, but with the first letter of each word
       capitalized. Pre: string contains words made of only letters, each separated
       by a single space."""

5. Read up on the format string method. Write a program that implements a “Mad Libs” style word game (see here if you’re not familiar with Mad Libs). First, prompt the user for a series of words, each a specific part of speech. Then fill the words into a story of your choice and print the story. Implement this program with only one call to the print function with only one argument. You may find it helpful to use triple-quoted strings so you can write your story on multiple lines.

6. Write a program to print a tidy, well-aligned table of characters and their corresponding character codes, starting with 32 and ending at 126. Make the character codes count by one going down each column. For extra fun, take a single command line argument that specifies how many columns your table should have. Example outputs:

   >>> %Run asciitable.py 6
    32     48 0   64 @   80 P   96 `  112 p  
    33 !   49 1   65 A   81 Q   97 a  113 q  
    34 "   50 2   66 B   82 R   98 b  114 r  
    35 #   51 3   67 C   83 S   99 c  115 s  
    36 $   52 4   68 D   84 T  100 d  116 t  
    37 %   53 5   69 E   85 U  101 e  117 u  
    38 &   54 6   70 F   86 V  102 f  118 v  
    39 '   55 7   71 G   87 W  103 g  119 w  
    40 (   56 8   72 H   88 X  104 h  120 x  
    41 )   57 9   73 I   89 Y  105 i  121 y  
    42 *   58 :   74 J   90 Z  106 j  122 z  
    43 +   59 ;   75 K   91 [  107 k  123 {  
    44 ,   60 <   76 L   92 \  108 l  124 |  
    45 -   61 =   77 M   93 ]  109 m  125 }  
    46 .   62 >   78 N   94 ^  110 n  126 ~  
    47 /   63 ?   79 O   95 _  111 o  
   >>> %Run asciitable.py 9
    32     43 +   54 6   65 A   76 L   87 W   98 b  109 m  120 x  
    33 !   44 ,   55 7   66 B   77 M   88 X   99 c  110 n  121 y  
    34 "   45 -   56 8   67 C   78 N   89 Y  100 d  111 o  122 z  
    35 #   46 .   57 9   68 D   79 O   90 Z  101 e  112 p  123 {  
    36 $   47 /   58 :   69 E   80 P   91 [  102 f  113 q  124 |  
    37 %   48 0   59 ;   70 F   81 Q   92 \  103 g  114 r  125 }  
    38 &   49 1   60 <   71 G   82 R   93 ]  104 h  115 s  126 ~  
    39 '   50 2   61 =   72 H   83 S   94 ^  105 i  116 t  
    40 (   51 3   62 >   73 I   84 T   95 _  106 j  117 u  
    41 )   52 4   63 ?   74 J   85 U   96 `  107 k  118 v  
    42 *   53 5   64 @   75 K   86 V   97 a  108 l  119 w