Python String zfill() Method - Learn By Example

Pads a string on the left with zeros

Usage

The zfill() method returns a copy of string left padded with ‘0’ characters to make a string of length width.

The original string is returned, if width is less than or equal to string length.

string.zfill(width)

Python string zfill() method parameters
Parameter	Condition	Description
width	Required	The length of the string with zeros padded to the left

# Zero-pad a string until it is 6 characters long
S = '42'
x = S.zfill(6)
print(x)
# Prints 000042

If the string contains a leading sign + or -, zeros are padded after the sign character rather than before.

S = '+42'
x = S.zfill(6)
print(x)
# Prints +00042

S = '-42'
x = S.zfill(6)
print(x)
# Prints -00042

You can achieve the same result by using format() method.

S = '42'
x = '{:0>6}'.format(S)
print(x)
# Prints 000042