How to retain leading zeros of int variables?

Question

Below is a section of code which is part of a functional decryption and encryption program.

while checkvar < maxvar: # is set to < as maxvar is 1 to high for the index of var
    #output.append("%02d" % number)
    i =ord(var[checkvar]) - 64 # Gets postional value of i
    i = ("%02d" % i)
    if (checkvar + 1) < maxvar:
        j =ord(var[(checkvar + 1)]) - 64 # Gets postional value of i
        j = ("%02d" % j)
        i = str(i) + str(j) #'Adds' the string i and j to create a new i
    li.append(int(i))
    checkvar = checkvar + 2

print li

As you can see the two variables i and j are first treated as string to add a 0 in front of any single digit numbers (as string). These variables then are combined to make a four digit number (still as a string). Later in the program the number created are used in a pow() function, as ints remove any leading zeros.

My question: Is it possible to force python to keep the leading zero for ints? I have and continued to search online.

Edit

To help people I have included the encryption part of the program. This is where the problem lies. The variables created in the above code are passed through a pow() function. As this can’t handle strings I have to convert the variables to ints where the leading zero is lost.

#a = li[]
b=int(17)#pulic = e
c=int(2773)#=n

lenli=int(len(li))
enchecker = int(0)

#encrpted list
enlist = []

while enchecker < lenli:
    en = pow(li[enchecker],b,c)#encrpyt the message can only handle int
    enlist.append(int(en))
    enchecker = enchecker + 1

print enlist

Asked By: Dan1676

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Source

Answer 1

The concept of leading zeros is a display concept, not a numerical one. You can put an infinite number of leading zeros on a number without changing its value. Since it’s not a numeric concept, it’s not stored with the number.

You have to decide how many zeros you want when you convert the number to a string. You could keep that number separately if you want.

Answered By: Mark Ransom

Answer 2

Though the comments above are true regarding 1, 01, and 001, are all the same as an int, it can be very helpful in temporal modeling, or sequential movie making to maintain the leading zeros. I do it often to ensure movie clips are in proper order. The easy way to do that is using zfill() to ensure the str version of the number has at least the number of characters you tell it, and does so by filling in the left-side of the string "number" with zeros.

>>> x = int(1)    
>>> NewStringVariable = str(x).zfill(3)    
>>> print NewStringVariable    
001    
>>> NewStringVariable = str(x).zfill(5)    
>>> print NewStringVariable    
00001

Answered By: user9297

Answer 3

I was getting date strings in the format of hhmmss coming from the serial line of my Arduino.

Suppose I got s = "122041"; this would be 12:20:41, however 9am would be 090000.

The statement print "%d" % (s) provokes a run time error because the 9 is not an octal number and is hence an illegal character.

To fix this problem:

print "%06d" % (int(s))

Answered By: julian lewis

Answer 4

Try this:

number = 1
print("%02d" % (number,))

or:

print("{:02d}".format(number))

The explanation of "%02d":

% – This tells the interpreter that a variable should be inserted here.

02 – This tells the interpreter to expect the variable to be 2 in length.

d – This tells the interpreter to expect a number, or should we say a"’d’igit".

Answered By: Gavriel Cohen

How to retain leading zeros of int variables?

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