Python: str (string)

Members of str

A list of members of str can be produced with dir:

for e in dir(str): print(e)

`__add__`
`__class__`
`__contains__`
`__delattr__`
`__dir__`
`__doc__`
`__eq__`
`__format__`
`__ge__`
`__getattribute__`
`__getitem__`
`__getnewargs__`
`__gt__`
`__hash__`
`__init__`
`__init_subclass__`
`__iter__`	String is an iterable (which allows `for` to iterate over a string's characters).
`__le__`
`__len__`
`__lt__`
`__mod__`
`__mul__`
`__ne__`
`__new__`
`__reduce__`
`__reduce_ex__`
`__repr__`
`__rmod__`
`__rmul__`
`__setattr__`
`__sizeof__`
`__str__`
`__subclasshook__`
`capitalize`, `lower`, `upper`, `swapcase`
`casefold`
`center`
`count`
`encode()`	returns a `bytes` object (encoding can be specified, is UTF-8 by default)
`endswith`, `startswith`	Checks if the string starts with or ends with a given string.
`expandtabs`
`find`, `rfind`
`format`
`format()`	probably what comes closest to the printf function of the C standard library.
`format_map`
`index`, `rindex`
`isalnum`
`isalpha`
`isascii`
`isdecimal`
`isdigit`
`isidentifier`
`islower`
`isnumeric`
`isprintable`
`isspace`
`istitle`
`isupper`
`join`
`ljust`, `rjust`	left/right alignment of a string. Compare with `zfill`
`lstrip`
`maketrans`	Used in conjunction with `translate(…)`.
`partition`, `rpartition`
`removeprefix`
`removesuffix`
`replace(old, new)`	replaces the text sequence `old` with `new` in `str`.
`str.rstrip()`	allows to remove aribtrary characters from the string's right side and thus can be used (almost) like Perl's `chomp()` function.
`split`, `rsplit`	Returns a list from the parts of the original string that are separated by the separator.
`splitlines()`	Splits a text on `\r`, `\n` or `\r\n` (i. e. on the traditional Unix, DOS and Mac line breaks).
`strip`
`title`
`translate(…)`
`zfill`	left-pads a string with zeroes: `print(str(42).zfill(5))` prints `00042`. Use `str(42).rjust(5, ' ')` to left pad the number with spaces.

Misc

Taking substrings from a string, for example to remove the last n characters from a string.

The built-in functions int() and float() can be used to convert a string to an integer and float, respectively.

Similarly, a numerical value can be converted to a string with str().

Strings are immutable

Strings are immutable. Thus, it is not possible to modify a string in place.

But see io.StringIO() for a way to somewhat simulate such a requirement.

Embedding expressions in a string

f-strings allow to embed expressions in a string. The expreassion is evaluated when the string is created, not when the string is evaluated:

>>> a = 2
>>> b = 3
>>> t = f"result = {a+b}"
>>> t
'result = 5'
>>> a=9
>>> t
'result = 5'

Repeating strings n times

A string is repeated n times with the multiplication operator ('text' * 5).

Reversing a string

A string can be reversed with the slicing notation [::-1]:

>>> 'abcdef'[::-1]
'fedcba'

Create a (simple!) regular expression to parse CSV files

nofFields = 10
csvregex = ';'.join(['([^;]*)'] * nofFields)