Python substring won't work with number integer
<p>So I am having trouble with the code in the way that it gives an error: "line 30, in 
    (ciphertextBinary[i])[x] = "0"
TypeError: 'str' object does not support item assignment".
 I have no idea as to why this happens as all that I am doing is changing a subtext of a string and replacing it with a string. If you can come up with any solutions it would be much obliged as I have looked for answers for a while now but have had no success. Before I had this error:</p>

<pre><code>     if (textBinary[i])[x] == (pad[i])[x]:
        (ciphertextBinary[i])[x] = "0"
    elif (textBinary[i])[x] != pad[i][x]:
        (ciphertextBinary[i])[x] = "1"
</code></pre>

<p>the code was not working and returned the input so I changed it to what I think would make it work but have come across this error instead.</p>

<pre><code>string = ""
string2 = ""
length = 0
lenght2 = 0
pad = ""


string = input("Enter String To Encrypt: ")
string2 = input("Enter PAD: ")

length = len(string)
length2 = len(string2)

textBinary = list(string)
pad = list(string2)
ciphertextBinary = list(string)
ciphertext = list(string)

for i in range(0, length):
    textBinary[i] = "{0:b}".format(ord(string[i]))
    for x in range(0, len(textBinary[i])):
        ciphertextBinary[i] = ciphertextBinary[i] + "a"

for i in range(0, length2):
    pad[i] = "{0:b}".format(ord(string2[i]))

for i in range(0, length):
    for x in range(0, len(textBinary[i])):
        if (textBinary[i])[x] == (pad[i])[x]:
            (ciphertextBinary[i])[x] = "0"
        elif (textBinary[i])[x] != pad[i][x]:
            (ciphertextBinary[i])[x] = "1"

for i in range(0, length):
    ciphertext[i] = int(ciphertextBinary[i], 2)
    print(chr(ciphertext[i]))
</code></pre>