Converting field to string with leading zeroes using Python Parser of ArcGIS Field Calculator?

Question

I would like to create an expression using the field calculator in ArcMap to be able to convert an Int field to a string and add leading zeroes.

I am able to do it in a python window with an example

x=450
print str(x).zfill(4)
>>>0450

I have tried:

!Time!.str().zfill(4)

but that gives me invalid syntax errors.

Answer 1

str is a class, not a method, so you need to do:

str(!Time!).zfill(4)

This should work if the Time field is an integer. If it's a float or other type, you will need to recast it as an int.