如何将字符串的特定部分移至新字符串

Question

For example, let's say I am using the following strings

key = "XPMGTDHLYONZBWEARKJUFSCIQV"
example = "test"
newKey = ""

and I want to get a random section of that string and I know the length. So

length = len(example)
rand = random.randint(0, len(key) - length)

I believe this code will take a random number from 0 to the length of the key minus the example. This should insure that I always have enough letters. The part I am getting stuck on, is how I take the starting point, rand, and the ending point, length, and use them to get a specific part of the key. For example, let's say rand = 2 and length = 4 . Then newKey should be, newKey = "MGTD" .

What string command can I use to get this result?

Answer 1

You can simply slice the key:

newKey = key[rand:rand + length]

Demo:

>>> length, rand = 4, 2
>>> key = "XPMGTDHLYONZBWEARKJUFSCIQV"
>>> key[rand:rand + length]
'MGTD'