Question

How can I assign the maximum value for a long integer to a variable, similar, for example, to C++’s LONG_MAX.

Answer 1

Long integers:

There is no explicitly defined limit. The amount of available address space forms a practical limit.
(Taken from this site). See the docs on Numeric Types where you’ll see that Long integers have unlimited precision. In Python 2, Integers will automatically switch to longs when they grow beyond their limit:

>>> import sys
>>> type(sys.maxsize)
<type 'int'>
>>> type(sys.maxsize+1)
<type 'long'>

for integers we have

maxint and maxsize:

The maximum value of an int can be found in Python 2.x with sys.maxint. It was removed in Python 3, but sys.maxsize can often be used instead. From the changelog:

The sys.maxint constant was removed, since there is no longer a limit
to the value of integers. However, sys.maxsize can be used as an
integer larger than any practical list or string index. It conforms to
the implementation’s “natural” integer size and is typically the same
as sys.maxint in previous releases on the same platform (assuming the
same build options).

and, for anyone interested in the difference (Python 2.x):

sys.maxint The largest positive integer supported by Python’s regular
integer type. This is at least 2**31-1. The largest negative integer
is -maxint-1 — the asymmetry results from the use of 2’s complement
binary arithmetic.

sys.maxsize The largest positive integer supported by the platform’s
Py_ssize_t type, and thus the maximum size lists, strings, dicts, and
many other containers can have.

and for completeness, here’s the Python 3 version:

sys.maxsize
An integer giving the maximum value a variable of type Py_ssize_t can take. It’s usually 2^31 – 1 on a 32-bit platform and
2^63 – 1 on a 64-bit platform.

floats:

There’s float("inf") and float("-inf"). These can be compared to other numeric types:

>>> import sys
>>> float("inf") > sys.maxsize
True