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There are four numeric types: plain integers, long integers,
floating point numbers, and complex numbers.
Plain integers (also just called integers)
are implemented using long in C, which gives them at least 32
bits of precision. Long integers have unlimited precision. Floating
point numbers are implemented using double in C. All bets on
their precision are off unless you happen to know the machine you are
working with.
Complex numbers have a real and imaginary part, which are both
implemented using double in C. To extract these parts from
a complex number z, use z.real and z.imag.
Numbers are created by numeric literals or as the result of built-in
functions and operators. Unadorned integer literals (including hex
and octal numbers) yield plain integers. Integer literals with an `L'
or `l' suffix yield long integers
(`L' is preferred because 1l looks too much like eleven!).
Numeric literals containing a decimal point or an exponent sign yield
floating point numbers. Appending j or J to a numeric
literal yields a complex number.
Python fully supports mixed arithmetic: when a binary arithmetic
operator has operands of different numeric types, the operand with the
``smaller'' type is converted to that of the other, where plain
integer is smaller than long integer is smaller than floating point is
smaller than complex.
Comparisons between numbers of mixed type use the same rule.
The functions int(), long(), float(),
and complex() can be used
to coerce numbers to a specific type.
All numeric types support the following operations, sorted by ascending priority (operations in the same box have the same priority; all numeric operations have a higher priority than comparison operations):
, Notes:
floor() and ceil() in
module math for well-defined conversions.
guido@CNRI.Reston.Va.US