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Diffstat (limited to 'Doc/library/functions.rst')
| -rw-r--r-- | Doc/library/functions.rst | 173 |
1 files changed, 121 insertions, 52 deletions
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst index cb9b650..c07b104 100644 --- a/Doc/library/functions.rst +++ b/Doc/library/functions.rst @@ -141,10 +141,11 @@ are always available. They are listed here in alphabetical order. See also :func:`format` for more information. -.. class:: bool(x=False) +.. class:: bool(object=False, /) - Return a Boolean value, i.e. one of ``True`` or ``False``. *x* is converted - using the standard :ref:`truth testing procedure <truth>`. If *x* is false + Return a Boolean value, i.e. one of ``True`` or ``False``. The argument + is converted using the standard :ref:`truth testing procedure <truth>`. + If the argument is false or omitted, this returns ``False``; otherwise, it returns ``True``. The :class:`bool` class is a subclass of :class:`int` (see :ref:`typesnumeric`). It cannot be subclassed further. Its only instances are ``False`` and @@ -153,7 +154,7 @@ are always available. They are listed here in alphabetical order. .. index:: pair: Boolean; type .. versionchanged:: 3.7 - *x* is now a positional-only parameter. + The parameter is now positional-only. .. function:: breakpoint(*args, **kws) @@ -371,29 +372,73 @@ are always available. They are listed here in alphabetical order. support for top-level ``await``, ``async for``, and ``async with``. -.. class:: complex(real=0, imag=0) - complex(string) +.. class:: complex(number=0, /) + complex(string, /) + complex(real=0, imag=0) + + Convert a single string or number to a complex number, or create a + complex number from real and imaginary parts. + + Examples: + + .. doctest:: + + >>> complex('+1.23') + (1.23+0j) + >>> complex('-4.5j') + -4.5j + >>> complex('-1.23+4.5j') + (-1.23+4.5j) + >>> complex('\t( -1.23+4.5J )\n') + (-1.23+4.5j) + >>> complex('-Infinity+NaNj') + (-inf+nanj) + >>> complex(1.23) + (1.23+0j) + >>> complex(imag=-4.5) + -4.5j + >>> complex(-1.23, 4.5) + (-1.23+4.5j) + + If the argument is a string, it must contain either a real part (in the + same format as for :func:`float`) or an imaginary part (in the same + format but with a ``'j'`` or ``'J'`` suffix), or both real and imaginary + parts (the sign of the imaginary part is mandatory in this case). + The string can optionally be surrounded by whitespaces and the round + parentheses ``'('`` and ``')'``, which are ignored. + The string must not contain whitespace between ``'+'``, ``'-'``, the + ``'j'`` or ``'J'`` suffix, and the decimal number. + For example, ``complex('1+2j')`` is fine, but ``complex('1 + 2j')`` raises + :exc:`ValueError`. + More precisely, the input must conform to the :token:`~float:complexvalue` + production rule in the following grammar, after parentheses and leading and + trailing whitespace characters are removed: - Return a complex number with the value *real* + *imag*\*1j or convert a string - or number to a complex number. If the first parameter is a string, it will - be interpreted as a complex number and the function must be called without a - second parameter. The second parameter can never be a string. Each argument - may be any numeric type (including complex). If *imag* is omitted, it - defaults to zero and the constructor serves as a numeric conversion like - :class:`int` and :class:`float`. If both arguments are omitted, returns - ``0j``. + .. productionlist:: float + complexvalue: `floatvalue` | + : `floatvalue` ("j" | "J") | + : `floatvalue` `sign` `absfloatvalue` ("j" | "J") + If the argument is a number, the constructor serves as a numeric + conversion like :class:`int` and :class:`float`. For a general Python object ``x``, ``complex(x)`` delegates to - ``x.__complex__()``. If :meth:`~object.__complex__` is not defined then it falls back - to :meth:`~object.__float__`. If :meth:`!__float__` is not defined then it falls back + ``x.__complex__()``. + If :meth:`~object.__complex__` is not defined then it falls back + to :meth:`~object.__float__`. + If :meth:`!__float__` is not defined then it falls back to :meth:`~object.__index__`. - .. note:: + If two arguments are provided or keyword arguments are used, each argument + may be any numeric type (including complex). + If both arguments are real numbers, return a complex number with the real + component *real* and the imaginary component *imag*. + If both arguments are complex numbers, return a complex number with the real + component ``real.real-imag.imag`` and the imaginary component + ``real.imag+imag.real``. + If one of arguments is a real number, only its real component is used in + the above expressions. - When converting from a string, the string must not contain whitespace - around the central ``+`` or ``-`` operator. For example, - ``complex('1+2j')`` is fine, but ``complex('1 + 2j')`` raises - :exc:`ValueError`. + If all arguments are omitted, returns ``0j``. The complex type is described in :ref:`typesnumeric`. @@ -682,21 +727,38 @@ are always available. They are listed here in alphabetical order. elements of *iterable* for which *function* is false. -.. class:: float(x=0.0) +.. class:: float(number=0.0, /) + float(string, /) .. index:: single: NaN single: Infinity - Return a floating point number constructed from a number or string *x*. + Return a floating point number constructed from a number or a string. + + Examples: + + .. doctest:: + + >>> float('+1.23') + 1.23 + >>> float(' -12345\n') + -12345.0 + >>> float('1e-003') + 0.001 + >>> float('+1E6') + 1000000.0 + >>> float('-Infinity') + -inf If the argument is a string, it should contain a decimal number, optionally preceded by a sign, and optionally embedded in whitespace. The optional sign may be ``'+'`` or ``'-'``; a ``'+'`` sign has no effect on the value produced. The argument may also be a string representing a NaN - (not-a-number), or positive or negative infinity. More precisely, the - input must conform to the ``floatvalue`` production rule in the following - grammar, after leading and trailing whitespace characters are removed: + (not-a-number), or positive or negative infinity. + More precisely, the input must conform to the :token:`~float:floatvalue` + production rule in the following grammar, after leading and trailing + whitespace characters are removed: .. productionlist:: float sign: "+" | "-" @@ -705,9 +767,10 @@ are always available. They are listed here in alphabetical order. digit: <a Unicode decimal digit, i.e. characters in Unicode general category Nd> digitpart: `digit` (["_"] `digit`)* number: [`digitpart`] "." `digitpart` | `digitpart` ["."] - exponent: ("e" | "E") ["+" | "-"] `digitpart` - floatnumber: number [`exponent`] - floatvalue: [`sign`] (`floatnumber` | `infinity` | `nan`) + exponent: ("e" | "E") [`sign`] `digitpart` + floatnumber: `number` [`exponent`] + absfloatvalue: `floatnumber` | `infinity` | `nan` + floatvalue: [`sign`] `absfloatvalue` Case is not significant, so, for example, "inf", "Inf", "INFINITY", and "iNfINity" are all acceptable spellings for positive infinity. @@ -723,26 +786,13 @@ are always available. They are listed here in alphabetical order. If no argument is given, ``0.0`` is returned. - Examples:: - - >>> float('+1.23') - 1.23 - >>> float(' -12345\n') - -12345.0 - >>> float('1e-003') - 0.001 - >>> float('+1E6') - 1000000.0 - >>> float('-Infinity') - -inf - The float type is described in :ref:`typesnumeric`. .. versionchanged:: 3.6 Grouping digits with underscores as in code literals is allowed. .. versionchanged:: 3.7 - *x* is now a positional-only parameter. + The parameter is now positional-only. .. versionchanged:: 3.8 Falls back to :meth:`~object.__index__` if :meth:`~object.__float__` is not defined. @@ -926,17 +976,36 @@ are always available. They are listed here in alphabetical order. with the result after successfully reading input. -.. class:: int(x=0) - int(x, base=10) +.. class:: int(number=0, /) + int(string, /, base=10) + + Return an integer object constructed from a number or a string, or return + ``0`` if no arguments are given. + + Examples: + + .. doctest:: + + >>> int(123.45) + 123 + >>> int('123') + 123 + >>> int(' -12_345\n') + -12345 + >>> int('FACE', 16) + 64206 + >>> int('0xface', 0) + 64206 + >>> int('01110011', base=2) + 115 - Return an integer object constructed from a number or string *x*, or return - ``0`` if no arguments are given. If *x* defines :meth:`~object.__int__`, - ``int(x)`` returns ``x.__int__()``. If *x* defines :meth:`~object.__index__`, - it returns ``x.__index__()``. If *x* defines :meth:`~object.__trunc__`, + If the argument defines :meth:`~object.__int__`, + ``int(x)`` returns ``x.__int__()``. If the argument defines :meth:`~object.__index__`, + it returns ``x.__index__()``. If the argument defines :meth:`~object.__trunc__`, it returns ``x.__trunc__()``. For floating point numbers, this truncates towards zero. - If *x* is not a number or if *base* is given, then *x* must be a string, + If the argument is not a number or if *base* is given, then it must be a string, :class:`bytes`, or :class:`bytearray` instance representing an integer in radix *base*. Optionally, the string can be preceded by ``+`` or ``-`` (with no space in between), have leading zeros, be surrounded by whitespace, @@ -966,7 +1035,7 @@ are always available. They are listed here in alphabetical order. Grouping digits with underscores as in code literals is allowed. .. versionchanged:: 3.7 - *x* is now a positional-only parameter. + The first parameter is now positional-only. .. versionchanged:: 3.8 Falls back to :meth:`~object.__index__` if :meth:`~object.__int__` is not defined. @@ -977,7 +1046,7 @@ are always available. They are listed here in alphabetical order. .. versionchanged:: 3.11 :class:`int` string inputs and string representations can be limited to help avoid denial of service attacks. A :exc:`ValueError` is raised when - the limit is exceeded while converting a string *x* to an :class:`int` or + the limit is exceeded while converting a string to an :class:`int` or when converting an :class:`int` into a string would exceed the limit. See the :ref:`integer string conversion length limitation <int_max_str_digits>` documentation. |