issue of string index out of range-CodePudding

When I try to implement my code an error appears, but when I use a debugger to see where the code's stuck there is no index out of range. I must miss something but I don't know what.

message = "WEATHERREPORTWINDYTODAY"
number1 = 7

def Encode(letter, number):
    shift = 0
    alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    liste_decode = []
    for i in range(len(letter)):
        number_index_alphabet = alphabet.index(letter[i])   shift   number
        shift  = 1
        if number_index_alphabet <= len(alphabet):
            liste_decode.append(alphabet[number_index_alphabet])
        else:
            number_index_alphabet -= 26
            liste_decode.append(alphabet[number_index_alphabet])

    return liste_decode
print(Encode(message, number1))

CodePudding user response：

Number_index_alphabet == 26 at some point. The index range for alphabet is 0-25 inclusive. You will have also problem with that line:

number_index_alphabet -= 26

Working code:

if number_index_alphabet < len(alphabet):
    liste_decode.append(alphabet[number_index_alphabet])
else:
    number_index_alphabet = number_index_alphabet % 26
    liste_decode.append(alphabet[number_index_alphabet])

CodePudding user response：

I see here two possible mistakes

if number_index_alphabet <= len(alphabet): should be if number_index_alphabet < len(alphabet):
not sure what you are expecting from this number_index_alphabet -= 26

I assume that your function should look like this

def Encode(letter, number):
    shift = 0
    alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    liste_decode = []
    for i in range(len(letter)):
        number_index_alphabet = alphabet.index(letter[i])   shift   number 
        shift  = 1
        liste_decode.append(alphabet[number_index_alphabet % 26])

    return liste_decode

CodePudding user response：

The reason why out of range is that you incremented shift and in one step of the loop number_index_alphabet will be 53, even if in the else statement you minus 26, you get 27, which is out of range.

And in the if statement number_index_alphabet <= len(alphabet) will also probably incur out of range error, should be number_index_alphabet < len(alphabet).

I guess you want to encode the sentence with a shift in the alphabet. changed a little bit, hope it helps.

message = "WEATHERREPORTWINDYTODAY"
number1 = 7

def Encode(letter, number):
    shift = number
    alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    str_encode = str()
    for i in range(len(letter)):
        number_index_alphabet = alphabet.index(letter[i])   shift
        
        if number_index_alphabet >= len(alphabet):
            number_index_alphabet %= len(alphabet)

        str_encode  = alphabet[number_index_alphabet]
            
    return str_encode

print(Encode(message, number1))

output: DLHAOLYYLWVYADPUKFAVKHF