How to downcase the first character of a string?

Question

There is a function to capitalize a string, I would like to be able to change the first character of a string to be sure it will be lowercase.

How can I do that in P

Answer 1

Simplest way:

>>> mystring = 'ABCDE'
>>> mystring[0].lower() + mystring[1:]
'aBCDE'
>>> 

Update

See this answer (by @RichieHindle) for a more foolproof solution, including handling empty strings. That answer doesn't handle None though, so here is my take:

>>> def first_lower(s):
   if not s: # Added to handle case where s == None
   return 
   else:
      return s[0].lower() + s[1:]

>>> first_lower(None)
>>> first_lower("HELLO")
'hELLO'
>>> first_lower("")
>>> 

Answer 2

One-liner which handles empty strings and None:

func = lambda s: s[:1].lower() + s[1:] if s else ''

>>> func(None)
>>> ''
>>> func('')
>>> ''
>>> func('MARTINEAU')
>>> 'mARTINEAU'