String split() and join()

It’s a common programming task is to take a large string and break it down into a bunch of substrings. The split() splits a string into a list of substrings called tokens. All the tokens combined form the larger string if put together.  A separator character indicated where to split up the string, to create the tokens. 

The join() method performs the opposite of split() by joining a list of strings together to create a big string.

The split() and join() methods are sometimes used together.

Other string methods

There are several useful string methods

• replace(old, new, count) - replace all old with new characters (up to count times)
• find(x, start, end) – find x, starting at start ending at end
• rfind(x) – reverse version of find()
• count(x) – returns number of occurrences of x
• isalnum() – returns True if all characters are numbers or letters only
• isdigit() – returns True if all characters are the numbers
• islower() – returns True if all letters are lowercase
• isupper() – return True if characters are uppercase
• isspace() – Return True if all characters are whitespace
• startswith(x) – return True if the string starts with x
• endswith(x) – return True if the string ends with x
• capitalize() – Returns a copy of the string with the first character capitalized and the rest lowercase
• lower() – Returns a copy of the string with all lowercase characters
• upper() – Returns a copy of the string with all uppercase characters
• strip() – Returns a copy of the string with leading and trailing whitespace removed
• title() – Returns a copy of the string as a title, with first letters of words capitalized

The arguments not in bold, that are italicized, are optional

String objects may be compared using relational operators (<, <=, >, >=), equality operators (==, !=), membership operators (in, not in), and identity operators (is, is not).