def encrypt(str_c):
result = ''
for i in str_c:
if i.islower():
result += chr((ord(i) - ord('a') + 4)%26 + ord('a'))
elif i.isupper():
result += chr((ord(i) - ord('A') + 4)%26 + ord('A'))
else:
result += i
return result
def decrypt(str_a):
result = ''
for i in str_a:
if i.islower():
# 这里和C语言不一样, python -3%26 = 23, C语言 -3%26 = -3
result += chr((ord(i) - ord('a') - 4)%26 + ord('a'))
elif i.isupper():
result += chr((ord(i) - ord('A') - 4)%26 + ord('A'))
else:
result += i
return result
# print(encrypt('i" laohu you wxyzaa..'))
print(decrypt(' ABCD'))