在python中切片字符串并将其转换为整数

Question

I've been trying to sort registration numbers. The registration number is of the format 18[az][az][az][0-9][0-9][0-9][0-9]

so I've tried this function

def cutt(n):
    n=int(n[5:9])

Is there something I need to return? It shows after using the function that it has a none datatype

Thank you

Answer 1

You should do like this:

def cutt(n):
    return int(n[5:9])

and in your code:

old_n = '18abc1234'
new_n = cutt(old_n)

the your new_n will be 1234 .

Answer 2

Use the code

def cutt(n):
    n=int(n[5:9])
    return n

Checking

val=cutt("18xyz3456")
print(val)

Output

3456

Hope it helps