There is an error in my code help me to correct it
This is the actual code
message=input("enter the message ")
alphabet='abcdefghijklmnopqrstuvwxyz '
key=5
encrypt=''
for i in message:
position=alphabet.find(i)
newposition=key+position
encrypt+=alphabet[newposition]
print(encrypt)
this is the error
IndexError: string index out of range
The error occurs when you enter a w x, y, z or space. position has the value 26 when find has found a space. Now you add 5 to your position which result in 31 and your string alphabet has only a length of 27.
So you have to rework the line
newposition=key+position
to get a valid number between 0 and 26. This can be done with modulo (or %) for example. You should convert the input string to lower case (or upper case and replacing your alphabet with upper case letter). Otherwise find doesn´t find any letter in your alphabet:
message="This is a test"
alphabet="abcdefghijklmnopqrstuvwxyz "
key=5
encrypt=""
for i in message.lower():
position=alphabet.find(i)
newposition=(key+position) % len(alphabet)
encrypt+=alphabet[newposition]
print(encrypt)
Which results in
Python 3.7.4 (default, Jul 9 2019, 00:06:43)
[GCC 6.3.0 20170516] on linux
y
ym
ymn
ymnx
ymnxf
ymnxfn
ymnxfnx
ymnxfnxf
ymnxfnxff
ymnxfnxfff
ymnxfnxfffy
ymnxfnxfffyj
ymnxfnxfffyjx
ymnxfnxfffyjxy
len(alphabet), its 27 actually
w, x, y and z as well
for i in message.lower():Your problem happens when
newposition = key + position
is larger than the length of your alphabet.
You can remedy your problem using modular arithmetic
newposition = (key + position) % len(alphabet)
This will happen if you have w, x, y, z or a (blank) in your input. Their positions in the string are 22, 23, 24, 25 and 26. respectively.Last position in alphabet is 26. 22 + 5 = 27, which is out of range, thus the error. Same for x, y, z and , which will give 28, 29, 30 and 31 respectively.
