RosettaCodeData/Task/Caesar-cipher/BASIC256/caesar-cipher.basic256

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# Caeser Cipher
# basic256 1.1.4.0
dec$ = ""
type$ = "cleartext "
input "If decrypting enter " + "<d> " + " -- else press enter > ",dec$ # it's a klooj I know...
input "Enter offset > ", iOffset
if dec$ = "d" then
iOffset = 26 - iOffset
type$ = "ciphertext "
end if
input "Enter " + type$ + "> ", str$
str$ = upper(str$) # a bit of a cheat really, however old school encryption is always upper case
len = length(str$)
for i = 1 to len
iTemp = asc(mid(str$,i,1))
if iTemp > 64 AND iTemp < 91 then
iTemp = ((iTemp - 65) + iOffset) % 26
print chr(iTemp + 65);
else
print chr(iTemp);
end if
next i