This module defines some constants useful for checking character
classes and some useful string functions. See the module
re for string functions based on regular
expressions.
The constants defined in this module are are:
- digits
-
The string '0123456789'.
- hexdigits
-
The string '0123456789abcdefABCDEF'.
- letters
-
The concatenation of the strings lowercase() and
uppercase() described below.
- lowercase
-
A string containing all the characters that are considered lowercase
letters. On most systems this is the string
'abcdefghijklmnopqrstuvwxyz'. Do not change its definition --
the effect on the routines upper() and
swapcase() is undefined.
- octdigits
-
The string '01234567'.
- uppercase
-
A string containing all the characters that are considered uppercase
letters. On most systems this is the string
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'. Do not change its definition --
the effect on the routines lower() and
swapcase() is undefined.
- whitespace
-
A string containing all characters that are considered whitespace.
On most systems this includes the characters space, tab, linefeed,
return, formfeed, and vertical tab. Do not change its definition --
the effect on the routines strip() and split()
is undefined.
The functions defined in this module are:
- atof (s)
-
Convert a string to a floating point number. The string must have
the standard syntax for a floating point literal in Python, optionally
preceded by a sign ("+" or "-"). Note that this behaves
identical to the built-in function
float() when passed a string.
- atoi (s[, base])
-
Convert string s to an integer in the given base. The
string must consist of one or more digits, optionally preceded by a
sign ("+" or "-"). The base defaults to 10. If it is
0, a default base is chosen depending on the leading characters of the
string (after stripping the sign): "0x" or "0X" means 16,
"0" means 8, anything else means 10. If base is 16, a
leading "0x" or "0X" is always accepted. Note that when
invoked without base or with base set to 10, this behaves
identical to the built-in function int() when passed a string.
(Also note: for a more flexible interpretation of numeric literals,
use the built-in function eval().)
- atol (s[, base])
-
Convert string s to a long integer in the given base. The
string must consist of one or more digits, optionally preceded by a
sign ("+" or "-"). The base argument has the same
meaning as for atoi(). A trailing "l" or "L" is
not allowed, except if the base is 0. Note that when invoked without
base or with base set to 10, this behaves identical to the
built-in function long() when passed a
string.
- capitalize (word)
-
Capitalize the first character of the argument.
- capwords (s)
-
Split the argument into words using split(), capitalize
each word using capitalize(), and join the capitalized
words using join(). Note that this replaces runs of
whitespace characters by a single space, and removes leading and
trailing whitespace.
- expandtabs (s, tabsize)
-
Expand tabs in a string, i.e. replace them by one or more spaces,
depending on the current column and the given tab size. The column
number is reset to zero after each newline occurring in the string.
This doesn't understand other non-printing characters or escape
sequences.
- find (s, sub[, start[,end]])
-
Return the lowest index in s where the substring sub is
found such that sub is wholly contained in
s[start:end]. Return -1 on failure.
Defaults for start and end and interpretation of negative
values is the same as for slices.
- rfind (s, sub[, start[, end]])
-
Like find() but find the highest index.
- index (s, sub[, start[, end]])
-
Like find() but raise ValueError when the
substring is not found.
- rindex (s, sub[, start[, end]])
-
Like rfind() but raise ValueError when the
substring is not found.
- count (s, sub[, start[, end]])
-
Return the number of (non-overlapping) occurrences of substring
sub in string s[start:end].
Defaults for start and end and interpretation of negative
values is the same as for slices.
- lower (s)
-
Convert letters to lower case.
- maketrans (from, to)
-
Return a translation table suitable for passing to
translate() or regex.compile(), that will map
each character in from into the character at the same position
in to; from and to must have the same length.
Warning: don't use strings derived from lowercase and
uppercase as arguments; in some locales, these don't have the
same length. For case conversions, always use lower() and
upper().
- split (s[, sep[, maxsplit]])
-
Return a list of the words of the string s. If the optional
second argument sep is absent or None, the words are
separated by arbitrary strings of whitespace characters (space, tab,
newline, return, formfeed). If the second argument sep is
present and not None, it specifies a string to be used as the
word separator. The returned list will then have one more items than
the number of non-overlapping occurrences of the separator in the
string. The optional third argument maxsplit defaults to 0. If
it is nonzero, at most maxsplit number of splits occur, and the
remainder of the string is returned as the final element of the list
(thus, the list will have at most maxsplit+1 elements).
- splitfields (s[, sep[, maxsplit]])
-
This function behaves identically to split(). (In the
past, split() was only used with one argument, while
splitfields() was only used with two arguments.)
- join (words[, sep])
-
Concatenate a list or tuple of words with intervening occurrences of
sep. The default value for sep is a single space
character. It is always true that
"string.join(string.split(s, sep), sep)"
equals s.
- joinfields (words[, sep])
-
This function behaves identical to join(). (In the past,
join() was only used with one argument, while
joinfields() was only used with two arguments.)
- lstrip (s)
-
Remove leading whitespace from the string s.
- rstrip (s)
-
Remove trailing whitespace from the string s.
- strip (s)
-
Remove leading and trailing whitespace from the string s.
- swapcase (s)
-
Convert lower case letters to upper case and vice versa.
- translate (s, table[, deletechars])
-
Delete all characters from s that are in deletechars (if
present), and then translate the characters using table, which
must be a 256-character string giving the translation for each
character value, indexed by its ordinal.
- upper (s)
-
Convert letters to upper case.
- ljust (s, width)
-
- rjust (s, width)
-
- center (s, width)
-
These functions respectively left-justify, right-justify and center a
string in a field of given width.
They return a string that is at least
width
characters wide, created by padding the string
s
with spaces until the given width on the right, left or both sides.
The string is never truncated.
- zfill (s, width)
-
Pad a numeric string on the left with zero digits until the given
width is reached. Strings starting with a sign are handled correctly.
- replace (str, old, new[, maxsplit])
-
Return a copy of string str with all occurrences of substring
old replaced by new. If the optional argument
maxsplit is given, the first maxsplit occurrences are
replaced.
This module is implemented in Python. Much of its functionality has
been reimplemented in the built-in module
strop. However, you
should never import the latter module directly. When
string discovers that strop exists, it transparently
replaces parts of itself with the implementation from strop.
After initialization, there is no overhead in using
string instead of strop.
