How to pad a string with leading zeros in Python 3

Question

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How to pad zeroes to a string? (14 answers)

Closed 5 months ago.

I'm trying to make length = 001 in Python 3 but whenever I try to print it out it truncates the value without the leading zeros (length = 1). How would I stop this happening without having to cast length to a string before printing it out?

Answer 1

I suggest this ugly method but it works:

length = 1
lenghtafterpadding = 3
newlength = '0' * (lenghtafterpadding - len(str(length))) + str(length)

I came here to find a lighter solution than this one!

Answer 2

There are many ways to achieve this but the easiest way in Python 3.6+, in my opinion, is this:

print(f"{1:03}")

Answer 3

Make use of the zfill() helper method to left-pad any string, integer or float with zeros; it's valid for both Python 2.x and Python 3.x.

Sample usage:

print str(1).zfill(3);
# Expected output: 001

Description:

When applied to a value, zfill() returns a value left-padded with zeros when the length of the initial string value less than that of the applied width value, otherwise, the initial string value as is.

Syntax:

str(string).zfill(width)
# Where string represents a string, an integer or a float, and
# width, the desired length to left-pad.

Answer 4

Python integers don't have an inherent length or number of significant digits. If you want them to print a specific way, you need to convert them to a string. There are several ways you can do so that let you specify things like padding characters and minimum lengths.

To pad with zeros to a minimum of three characters, try:

length = 1
print(format(length, '03'))

Answer 5

Since python 3.6 you can use fstring :

>>> length = 1
>>> print(f'length = {length:03}')
length = 001