Strings and their methods

A string is a sequence of characters, and each character has a position number starting from zero: date[0] is the first character and date[-1] is the last. You can take part of a string with slicing: date[:4] gives you the first four characters and date[-2:] the last two. Note that the start position is included in the slice and the end position is not.

Most text is typed by people, so it comes with stray spaces and a mix of upper and lower case. That's why strings have built-in methods you call after a dot: strip() removes spaces from both ends, lower() and upper() convert letters to lower or upper case, replace(a, b) swaps one piece of text for another, split() breaks the string into a list of words, and "-".join(words) joins words into one string with the separator of your choice between them.

Remember that a string can't be changed. If you write title.lower() on a line by itself, title stays exactly as it was, because the method returns a new string that you need to store in a variable. Also note that split() with empty parentheses ignores repeated spaces, while split(" ") gives you empty strings between them.