In the code below, s refers to a string (although I have tried converting it to a list and I still have the same problem).
s = "".join(s)
if s[-1] == "a":
s += "gram"
I the last item in the string is the letter "a", then the program needs to add the string "gram" to the end of the string 's' represents.
e.g. input:
s = "insta"
output:
instagram
But I keep getting an IndexError, any ideas why?
If s is empty string s[-1] causes IndexError:
>>> s = ""
>>> s[-1]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: string index out of range
Instead of s[-1] == "a", you can use s.endswith("a"):
>>> s = ""
>>> s.endswith('a')
False
>>> s = "insta"
>>> s.endswith('a')
True
IndexError.
IndexError is only raised if s is empty.If s is empty, there is no last letter to test:
>>> ''[-1]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: string index out of range
Use str.endswith() instead:
if s.endswith('a'):
s += 'gram'
str.endswith() does not raise an exception when the string is empty:
>>> 'insta'.endswith('a')
True
>>> ''.endswith('a')
False
Alternatively, using a slice would also work:
if s[-1:] == 'a':
as slices always return a result (at minimum an empty string) but str.endswith() is more self-evident as to what it does to the casual reader of your code.
str.endswith() is self-documenting it's purpose here.