Unit 1

[10.1] You are given a string s. How would you:

1. Get the first letter of the string
2. Get the last letter of the string
3. Get the 5th letter of the string (assuming the string has at least 6 letters)

1. first_letter = s[0]
2. last_letter = s[len(s)-1]
3. fifth_letter = s[4]

[10.2] You are given the string s = “My name is Mira”.

1. Get the substring “name” and store it into a variable.
2. Get the substring “Mira” and store it into a variable.
3. Now create a new string that says “name: Mira”.
4. Now create a new string that says “NAME: MIRA”.

s = "My name is Mira"

#1
name = s[3:7]

#2
mira = s[11:]

#3
s1 = name + ": " + mira

#4
s2 = name.upper() + ": " + mira.upper()

[10.3] Print a string that uses double quotation marks inside the string.

print('This is a string with "double quotation marks" inside.')

[10.4] Print a string that uses an apostrophe inside the string.

print("This is a string with an apostrophe (') inside.")

[10.5] Print the string “zing” by using slice notation on the string “bazinga” to specify the correct range of characters.

s1 = "bazinga"
s2 = s1[2:6]  # range from index 2 to index 6 (exclusive)
print(s2)

[10.6] Create two strings, concatenate them and then print the resulting string.

string1 = "Hello "
string2 = "World"
result = string1 + string2
print(result)

[10.7] Create a string variable. Print the string and its length

myString= "Hello, World!"
print("String:", myString)
print("Length:", len(myString))

[10.8] Create the string “aweawesomesome” from the given string s=”awesome”.

s = "awesome"
resulting_string = s[0:3] + s + s[3:]
print(resulting_string)

[10.9] Modify the above code so that the printed string is reversed.

meal = "cheesecake, steak, fries"
for i in range(len(meal) - 2, -1, -2):
    print(meal[i])

[10.10] Given two strings, s1 and s2. Write a few lines of code to create a new string s3 by appending s2 in the middle of s1. If the string length is odd, the end of the string will have the extra letter. For example, if the length of s1 was 13, s3 would have 6 characters of s1, then s2, then 7 characters of s1.

s1 = "Ault"
s2 = "Kelly"

# Find the midpoint of s1
midpoint = len(s1) // 2

# Insert s2 at the midpoint of s1
s3 = s1[:midpoint] + s2 + s1[midpoint:]

# Print the result
print(s3)

[10.11] Write a few lines of code that converts the following strings to lowercase: "Animals", "Badger", "Honey Bee", "Honey Badger".

s1 = "Animals"
s2 = "Badger"
s3 = "Honey Bee"
s4 = "Honey Badger"

print(s1.lower())
print(s2.lower())
print(s3.lower())
print(s4.lower())

[10.12] Repeat the above exercise, but convert each string to uppercase instead of lowercase.

s1 = "Animals"
s2 = "Badger"
s3 = "Honey Bee"
s4 = "Honey Badger"

print(s1.upper())
print(s2.upper())
print(s3.upper())
print(s4.upper())

[10.13] Write a few lines of code that removes whitespace from the following strings, then print out the strings with the whitespace removed:

string1 = " FiletMignon" 
string2 = "Brisket " 
string3 = " Cheeseburger "

string1 = " FiletMignon" 
string2 = "Brisket " 
string3 = " Cheeseburger "

print(string1.strip())
print(string2.strip())
print(string3.strip())

[10.14] Write the function checkTwos that takes in a string as a parameter and returns True if the second character and the second to last character of the string are the same. You are guaranteed that the string will be at least 4 characters long.

def checkTwos(s):
    # compare the second character with the second-to-last character
    return s[1] == s[len(s) - 2]

# test the function
print(checkTwos("abba"))  # Output: True
print(checkTwos("programming"))  # Output: False

[10.15] Given a string of numbers and characters, write the function numsOnly that returns all the numbers in the string in the same order they occur (in string form).

def numsOnly(s):
    result = ""
    for char in s:
        if char.isdigit():
            result += char
    return result

print(numsOnly("o23yay9"))  # Output: "239"
print(numsOnly("hello"))     # Output: ""
print(numsOnly("I have 1 infinite loop, 5 assertion errors, 11 bugs and 0 motivation right now."))  # Output: "15110"

[10.16] Write a function matchString that takes in two strings, one a sentence and a word, and returns how many times the word occurs in the sentence. Be careful of casing - we are counting the word regardless of if it is lowercase vs uppercase.

def matchString(sentence, word):
    sentenceLower = sentence.lower()
    wordLower = word.lower()
    return sentenceLower.count(wordLower)

print(matchString("Programming is fun, programming is creative", "programming")) # Output: 2 
print(matchString("The cat with the red hat on the blue mat.", "the")) # Output: 3

[10.17] Write the function numFun that takes a string as a paramter. The function should print the number of digits in the string and should return the average of these numbers.

def numFun(s):
    total = 0
    count = 0
    
    for i in range(len(s)):
        if s[i].isdigit():
            total += int(s[i])
            count += 1
    
    avg = total / count
    
    print("Count:", count)
    
    return avg

print(numFun("PYnative29@#8496"))   # Prints 6, Returns: 6.333333333333333
print(numFun("jhfbjadj198ksjn98")) # Prints 5, Returns: 7.0

[10.18] Write the function splicedCheck that takes in two indexes and a string as a paramter and returns the substring obtained by slicing the string starting from the first given index up to and including the character of the second index. Remember spaces also have associated indexes!

def splicedCheck(start, end, s):
    return s[start:end+1]

print(splicedCheck(0, 4, "HelloWorld!"))        # Output: "Hello"
print(splicedCheck(3, 9, "I wish I could sleep")) # Output: "ish I c"

[10.19] Write the function count_characters that takes input from the user and displays the number of characters in the given input.

def count_characters():
    userInput = input("Enter a string: ")
    numCharacters = len(userInput)
    print("Number of characters:", numCharacters)
    
count_characters()

[10.20] Write the function not_string that takes a string as a paramter and returns a new string where the string "not " has been added to the front. However, if the string already begins with "not", return the string unchanged.

def not_string(s):
    if s.startswith("not"):
        return s
    else:
        return "not " + s

# Test cases
print(not_string('candy'))    # Output: 'not candy'
print(not_string('x'))        # Output: 'not x'
print(not_string('not bad'))  # Output: 'not bad'

[10.21] Write the function count_characters that takes a string as a parameter and counts and prints all letters, digits, and special symbols from the given string.

def count_characters(s):
    chars = 0
    digits = 0
    symbols = 0

    for i in range(len(s)):
        if s[i] in "abcdefghijklmnopqrstuvwxyz" or s[i] in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
            chars += 1
        elif s[i].isdigit():
            digits += 1
        else:
            symbols += 1

    print("Chars =", chars)
    print("Digits =", digits)
    print("Symbols =", symbols)

# Test the function
str1 = "P@#yn26at^&i5ve"
count_characters(str1)

[10.22] Write a function count_vowels that takes a sentence as paramter and counts the number of vowels in the sentence (a, e, i, o, u). Count for both upper and lower case vowels.

def count_vowels(sentence):
    vowels = "aeiou"
    count = 0
    
    # Convert the sentence to lowercase to handle case-insensitivity
    sentence = sentence.lower()
    
    # Iterate through each character in the sentence
    for i in range(len(sentence)):
        # Check if the character is a vowel
        if sentence[i] in vowels:
            count += 1
    
    return count

# Test the function
sentence = input("Enter a sentence: ")
num_vowels = count_vowels(sentence)
print("Number of vowels in the sentence:", num_vowels)

[10.23] What is the output of the following code?

s = 'abcdef'
t = s[0] + s[5] + s[len(s) - 5]

print(t)

[10.24] Trace through this code. What is printed at the end, once all the code is executed?

s1 = "I"
s2 = s1
print(s2 + " ")
s1 = "LOCO"
s3 = "DINGVE"
print(s1[0:2] + s3[4:len(s3)] + " ")
s4 = s3[0:4] + "!"
print(s4)

I 
LOVE 
DING!

[10.25] Trace through this code below. What is printed at the end?

s = "hi my name is"
for i in range(1, len(s)):
    s[i] = s[i-1]
print(s[1:])

[10.26] Trace through the code below. What does the function call return? What is printed?

def mysteryStringFun(s1, n):
    new_s = ""
    for i in range(n):
        new_s += s1[i] * i
    return new_s + s1[n-1:]

some_s = "CMU is fun!"
print("original: ", some_s)
print("function returns: ", mysteryStringFun(some_s, 5))

original:  CMU is fun!
function returns:  MUU   iiiiis fun!

[10.27] Trace through the code below. What does it print?

meal = "cheesecake, steak, fries"
for i in range(0, len(meal), 2):
    print(meal[i])

c
e
s
c
k
,
s
e
k
 
r
e

[10.28] What will be the output of the following code?

word = "python is awesome"
index = 0
while index < len(word):
    print(word[index])
    index += 2

p
t
o
 
s
a
e
o
e