Python Tips- Maximum Value float('inf')

In Python, there are two types: 'int' and 'float'. It's important to note that in Python 3, integers (int) have no maximum limit.
Here is a question: what is the maximum value in Python?

For the float, we can use sys.float_info to check the details.

>>> import sys
>>> sys.float_info
sys.float_info(max=1.7976931348623157e+308, max_exp=1024, max_10_exp=308, min=2.2250738585072014e-308, min_exp=-1021, min_10_exp=-307, dig=15, mant_dig=53, epsilon=2.220446049250313e-16, radix=2, rounds=1)

>>> print(sys.float_info.max)
1.7976931348623157e+308

The float value range is

-1.7976931348623157e+308 <= f <= 1.7976931348623157e+308

Also, we can declare the max value in float

>>> a = float('inf')
>>> a
inf
>>> import math
>>> math.isinf(a)
True
>>> 
>>> b = math.inf
>>> math.isinf(b)
True

We can compare 'inf' and float_info.max

>>> a > sys.float_info.max
True

How about the max value of 'int'? It is a 64 bit value.

>>> sys.maxsize
9223372036854775807
>>> 
>>> 
>>> print(sys.maxsize == 2**63 - 1)
True

But sys.maxsize is not the max int value, you can declare a value

>>> b = 10**309
>>> type(b)
<class 'int'>
>>> b>sys.float_info.max
True
>>> b>sys.maxsize 
True
>>> b > float('inf')
False

So, if you want to know why the Integer (int) has no max limit in Python, you need read the source code, the int object is with variable size.

typedef struct _longobject PyLongObject;
struct _longobject {
  PyObject_VAR_HEAD
  digit ob_digit[1];
};
#define PyObject_VAR_HEAD      PyVarObject ob_base;
typedef struct {
    PyObject ob_base;
    Py_ssize_t ob_size; /* Number of items in variable part */
} PyVarObject;
typedef struct _object {
    _PyObject_HEAD_EXTRA
    Py_ssize_t ob_refcnt;
    struct _typeobject *ob_type;
} PyObject;

Image is from [5].

Please refer to [6] to read the source code in C~

In summary, we can use float('inf') as the max value in Python. For the float, we max value is sys.float_info.max. for the integer, we can use the value sys.maxsize. But Integer (int) has no max limit in Python 3, from the source code in C language, the int object is defined variable size, that is why it has no max limit. Actually, the maximum integer value depends on the memory size, you can try~

Reference

[1.Maximum and minimum float values in Python]
https://note.nkmk.me/en/python-sys-float-info-max-min/
[2.Integer (int) has no max limit in Python 3]
https://note.nkmk.me/en/python-int-max-value/
[3.numeric-types-int-float-complex]
https://docs.python.org/3/library/stdtypes.html#numeric-types-int-float-complex
[4.Int object source code ]
https://fasionchan.com/python-source/builting-object/int/
[5.Int object]
https://juejin.cn/post/7209612932367597623
[6.Python source code]
https://github.com/python/cpython/blob/v3.7.0/Objects/longobject.c#L3