len function, when applied to a string, returns the number of characters in a string.
To get the last letter of a string, you might be tempted to try something like this:
That won’t work. It causes the runtime error
IndexError: string index out of range. The reason is that there is no
letter at index position 6 in
Since we started counting at zero, the six indexes are
numbered 0 to 5. To get the last character, we have to subtract 1 from
the length. Give it a try in the example above.
Alternatively in Python, we can use negative indices, which count backward from the
end of the string. The expression
fruit[-1] yields the last letter,
fruit[-2] yields the second to last, and so on. Try it!
Most other languages do not allow the negative indices, but they are a handy feature of Python!
Check your understanding