# ---------- STRING METHODS ----------

# Strings have many methods we can use beyond what I covered last time

rand_string = " this is an important string "

# Delete whitespace on left

rand_string = rand_string.lstrip()

# Delete whitespace on right

rand_string = rand_string.rstrip()

# Delete whitespace on right and left

rand_string = rand_string.strip()

# Capitalize the 1st letter

print(rand_string.capitalize())

# Capitalize every letter

print(rand_string.upper())

# lowercase all letters

print(rand_string.lower())

# Turn a list into a string and separate items with the defined

# separator

a_list = ["Bunch", "of", "random", "words"]

print(" ".join(a_list))

# Convert a string into a list

a_list_2 = rand_string.split()

for i in a_list_2:

print(i)

# Count how many times a string occurs in a string

print("How many is :", rand_string.count("is"))

# Get index of matching string

print("Where is string :", rand_string.find("string"))

# Replace a substring

print(rand_string.replace("an ", "a kind of "))

# ---------- PROBLEM : ACRONYM GENERATOR ----------

# You will enter a string and then convert it to an acronym

# with uppercase letters like this

'''

Convert to Acronym : Random Access Memory

RAM

'''

# Ask for a string

orig_string = input("Convert to Acronym : ")

# Convert the string to all uppercase

orig_string = orig_string.upper()

# Convert the string into a list

list_of_words = orig_string.split()

# Cycle through the list

for word in list_of_words:

# Get the 1st letter of the word and eliminate the newline

print(word[0], end="")

print()

# ---------- MORE STRING METHODS ----------

# For our next problem some additional string methods are going to be

# very useful

letter_z = "z"

num_3 = "3"

a_space = " "

# Returns True if characters are letters or numbers

# Whitespace is false

print("Is z a letter or number :", letter_z.isalnum())

# Returns True if characters are letters

print("Is z a letter :", letter_z.isalpha())

# Returns True if characters are numbers (Floats are False)

print("Is 3 a number :", num_3.isdigit())

# Returns True if all are lowercase

print("Is z a lowercase :", letter_z.islower())

# Returns True if all are uppercase

print("Is z a uppercase :", letter_z.isupper())

# Returns True if all are spaces

print("Is space a space :", a_space.isspace())

# ---------- MAKE A isfloat FUNCTION ----------

# There is no way to check if a string contains a float

# so let's make one by defining our own function

# Functions allow use to avoid repeating code

# They can receive values (attributes / parameters)

# They can return values

# You define your function name and the names for the values

# it receives like this

def isfloat(str_val):

try:

# If the string isn't a float float() will throw a

# ValueError

float(str_val)

# If there is a value you want to return use return

return True

except ValueError:

return False

pi = 3.14

# We call our functions by name and pass in a value between

# the parentheses

print("Is Pi a Float :", isfloat(pi))

# ---------- PROBLEM : CAESAR'S CIPHER ----------

# Receive a message and then encrypt it by shifting the

# characters by a requested amount to the right

# A becomes D, B becomes E for example

# Also decrypt the message back again

# A-Z have the numbers 65-90 in unicode

# a-z have the numbers 97-122

# You get the unicode of a character with ord(yourLetter)

# You convert from unicode to character with chr(yourNumber)

# You should check if a character is a letter and if not

# leave it as its default

# Hints

# Use isupper() to decided which unicodes to work with

# Add the key (number of characters to shift) and if

# bigger or smaller then the unicode for A, Z, a, or z

# increase or decrease by 26

# Receive the message to encrypt and the number of characters to shift

message = input("Enter your message : ")

key = int(input("How many characters should we shift (1 - 26)"))

# Prepare your secret message

secret_message = ""

# Cycle through each character in the message

for char in message:

# If it isn't a letter then keep it as it is in the else below

if char.isalpha():

# Get the character code and add the shift amount

char_code = ord(char)

char_code += key

# If uppercase then compare to uppercase unicodes

if char.isupper():

# If bigger than Z subtract 26

if char_code > ord('Z'):

char_code -= 26

# If smaller than A add 26

elif char_code < ord('A'):

char_code += 26

# Do the same for lowercase characters

else:

if char_code > ord('z'):

char_code -= 26

elif char_code < ord('a'):

char_code += 26

# Convert from code to letter and add to message

secret_message += chr(char_code)

# If not a letter leave the character as is

else:

secret_message += char

print("Encrypted :", secret_message)

# To decrypt the only thing that changes is the sign of the key

key = -key

orig_message = ""

for char in secret_message:

if char.isalpha():

char_code = ord(char)

char_code += key

if char.isupper():

if char_code > ord('Z'):

char_code -= 26

elif char_code < ord('A'):

char_code += 26

else:

if char_code > ord('z'):

char_code -= 26

elif char_code < ord('a'):

char_code += 26

orig_message += chr(char_code)

else:

orig_message += char

print("Decrypted :", orig_message)

# ---------- EXTRA HOMEWORK ----------

# For homework put the duplicate code above in a function