Python numeric string left 0 __python

As a news crawler, the URL inside 0-9 of the date to the left plus 0. Two methods were obtained after the query.

First, set a large enough number, such as 1000000, and then add the current number such as 9, get 1000009, and then converted to a string to get 6th, 7 bits. Let's take 1000 for example.

k=1000  #k是用来获取01 02 03 String   1001  intercept the 34th bit for the I in
Range (1,31):
    strtime=i+k
    time=str (strtime ) [2:4]
    print (len (time))

Second, get the current string length, then use the expected length-the current string length of the number should be zero, the corresponding 0 to the corresponding left.