Please Use the provided code

## caesar.py

def encode$($msg$,$ shift$)$:

newmsg $=""$

#process each character in msg$.$

#Hint: using a for loop

#A for loop to check each ch in msg:

if $(\text{'}$A ch and ch Z$\text{'})$: #if the character is an uppercase letter

#encode the character based on the shift number

#Hint: the new character newch should be

#chr$(($ord$($ch$)-$ ord$(\text{'}$A$\text{'})+$ shift$)\%26+$ ord$(\text{'}$A$\text{'}))$

elif $(\text{'}$a ch and ch z$\text{'})$: #if the character is a lowercase letter

#Hint: Do similar thing to the above transformation

else: #if the character is not alphabetic

#Hint: What does the assignment ask you to do with such character?

#After the character is transformed, not put it as part of the new message

#Hint: which variables hold the new message and new character?

return newmsg

msg $=$ input$("$Enter message to be encrypted: $")$

shiftstr $=$ input$("$Enter shift amount $(1-25)$: $")$

shift $=$ int$($shiftstr$)$

print$("$Encrypted message: $"+$ encode$($msg$,$ shift$))$

$1.$ You need to define a function encode$($msg$,$ shift$)$ that has two parameters: a message

to be encoded and a shift number

$2.$ In the function definition, you can use a for loop to enumerate every character in the

original message.

for ch in msg:

#check ch and modify it if needed

$3.$ How to code a letter with a shift number?

When encoding a message, each upper$/$lower case letter is coded into another

upper$/$lower case letter based on the shift number. For example, if the shift number

is

$3,$ letter $$H$$ is coded into $$K$,$ letter $$o$$ is coded into $$r$,$ letter $$z$$ is coded into $$c$$

$($wrap$-$around problem$).$

Two functions ord$()$ and chr$()$ are useful for the coding. The ord$()$ function generates

the ASCII integer value of a character. For example, typing the following in Python

interpreter,

$>>>$ ord$(\text{'}$a$\text{'})97$

$>>>$ ord$(\text{'}$A$\text{'})65$

The inverse to the ord$()$ function is the chr$()$ function. If you try the following in the

Python shell:

$>>>$ chr$(65)$

$\text{'}$A$\text{'}$

$>>>$ chr$(65+3)$

$\text{'}$D$\text{'}$

$>>>$ chr$(97)\text{'}$a$\text{'}$

To handle the wrap$-$around problem for an upper letter, use the expression

chr$(($ord$($ch$)-$ ord$(\text{'}$A$\text{'})+$ shift$)\%26+$ ord$(\text{'}$A$\text{'}))$

$3$

to calculate the encrypted version of an upper$-$case letter, where ch stores the letter

and shift stores the shift number. $($You will need a similar expression for the lowercase letters.$)$ For example, if ch holds letter $$B$,$

$>>>$ ch $=\text{'}$B$\text{'}$

$>>>$ shift $=3>>>$

print$($ch$)$

B

$>>>$ ch $=$ chr$(($ord$($ch$)-$ ord$(\text{'}$A$\text{'})+$ shift$)\%26+$ ord$(\text{'}$A$\text{'}))$

$>>>$ print$($ch$)$

E

Let$$s see another example: if ch holds letter $$Z$,$

$>>>$ ch $=\text{'}$Z$\text{'}$

$>>>$ ch $=$ chr$(($ord$($ch$)-$ ord$(\text{'}$A$\text{'})+$ shift$)\%26+$ ord$(\text{'}$A$\text{'}))$

$>>>$ print$($ch$)$

$\text{'}$C$\text{'}$

$>>>$

$4.$ Note that a string object in Python is immutable. When you encrypt the input

message, you can create a new encrypted message by

#at the beginning newmsg

$=""$

#later while looping over each ch on the old message, you can

#make new message by attaching the new character encoded

# with the on$-$progress new message newmsg $=$

newmsg $+$ newch

where ch holds the encoded character.

$5.$ You can use input$()$ to read a string from standard input $($default device connecting

to keyboard$).($You can use raw input$()$ if your Python is older version.$)$ For example,

typing the following in Python interpreter:

$>>>$ msg $=$ input$("$Enter message to be encrypted: $")$

Enter message to be encrypted: hello world

$>>>$ print$($msg$)$ hello

world

$6.$ You can read a shift number string from standard input $($default device connectingto

keyboard$)$ and transform the string to a number. For example, you may reference the

functions in the following sequence:

$>>>$ shiftstr $=$ input$("$Enter shift amount $(1-25)$:$")$

Enter shift amount $(1-25)$:$23$

$>>>$ shift $=$ int$($shiftstr$)$

$4$

$>>>$ print$($shift$)$

$23$

##

caesar.py

def encode$($msg$,$ shift$)$:

newmsg $="$n

#process each character in msg$.$

#Hint: using a for loop

#A for loop to check each ch in msg:

#encode the character based on the shift number

#Hint: the new character newch should be

#chr $((ord(ch)-$ord${(}^{\text{'}}{A}^{\text{'}})+$shift$)\%26+$ord${(}^{\text{'}}{A}^{\text{'}}))$

#Hint: Do similar thing to the above transformation

else: #if the character is not alphabetic

#Hint: What does the assignment ask you to do with such character?

#After the character is transformed, not put it as part of the new message

#Hint: which variables hold the new message and new character?

return newmsg

msg $=$ input$("$Enter message to be encrypted: $")$

shiftstr $=$ input$("$Enter shift amount $(1-25)$: $")$

shift $=$ int$($shiftstr$)$

print$("$Encrypted message: $"+$ encode$($msg$,$ shift$))$

If you run your program with input as in the below examples, your program output should be same as illustrated.

$>>>================================$ RESTART $================================$

$>>>$

Enter message to be encrypted: Hello World

Enter shift amount $(1-25)$: $3$

Encrypted message: Khoor Zruog

$>>>================================$ RESTART $================================$

$>>>$

Enter message to be encrypted: Khoor