两个几乎相同的python文件提供不同的输出

Question

I'm learning python at school for computing coursework and on an encryption related task me and a friend have come on a rather curious error: We each have our own copy of the program, one of which uses an "or" in the if statement that decides whether the program is encrypting or decrypting, this is the only difference, has anyone got any idea as to why this should be affecting the program? The program intends to take an input from the user and then return the encrypted string where each character has been moved 5 letters along in the alphabet, the decryption option does the inverse of this, both the working and none working programs are below:

Working Program

mode = input("Do you want to encrypt or decrypt\t")
x=1
while x == 1:
    Raw_input = input('Write Text: ')
    Raw_input = Raw_input.lower()
    output = []
    printOut = str()
    if mode == "decrypt":
        for character in Raw_input:
            number = ord(character) + 91
            if number < 193:
                number += 26
            output.append(number)
        length = len(output)
        for counter in range (length):
            character = chr((output[counter])-96) 
            printOut = printOut + character
    elif mode == "encrypt":
        for character in Raw_input:
            number = ord(character) - 91
            if number > 26:
                number -= 26
            output.append(number)
        length = len(output)
        for counter in range (length):
            character = chr((output[counter])+96) 
            printOut = printOut + character
    print(printOut)

Not Working Program

mode = input("Do you want to encrypt or decrypt\t")
x=1
while x == 1:
    Raw_input = input('Write Text: ')
    Raw_input = Raw_input.lower()
    output = []
    printOut = str()
    if mode == "decrypt" or "d":
        for character in Raw_input:
            number = ord(character) + 91
            if number < 193:
                number += 26
            output.append(number)
        length = len(output)
        for counter in range (length):
            character = chr((output[counter])-96) 
            printOut = printOut + character
    elif mode == "encrypt" or "e":
        for character in Raw_input:
            number = ord(character) - 91
            if number > 26:
                number -= 26
            output.append(number)
        length = len(output)
        for counter in range (length):
            character = chr((output[counter])+96) 
            printOut = printOut + character
    print(printOut)

It only Appears to be the encryption that doesnt work on the problem code, it will easily decrypt what the working code returns.

Thanks in advance for any help Given :)

Answer 1

if mode == "decrypt" or "d":

is always True, you probably mean

if mode == "decrypt" or mode == "d":

so the first branch is always taken. Likewise for

elif mode == "encrypt" or mode == "e":

Answer 2

if mode == 'encrypt' or 'e': Will always evaluate to True because 'e' is True

You need to be using:

if mode == 'encrypt' or mode == 'e':

or for a more comprehensive check:

if mode.lower().strip() in ['encrypt', 'e']: