Numbers
These are created by numeric literals and returned as results by arithmetic operators and arithmetic built-in functions. Numeric objects are immutable; once created their value never changes. Python numbers are of course strongly related to mathematical numbers, but subject to the limitations of numerical representation in computers.
Python distinguishes between integers, floating point numbers, and complex numbers:
Integers
These represent elements from the mathematical set of integers (positive and negative).
There are three types of integers:
Plain integers
These represent numbers in the range -2147483648 through 2147483647. (The range may be larger on machines with a larger natural word size, but not smaller.) When the result of an operation would fall outside this range, the result is normally returned as a long integer (in some cases, the exception OverflowError is raised instead). For the purpose of shift and mask operations, integers are assumed to have a binary, 2's complement notation using 32 or more bits, and hiding no bits from the user (i.e., all 4294967296 different bit patterns correspond to different values).
Long integers
These represent numbers in an unlimited range, subject to available (virtual) memory only. For the purpose of shift and mask operations, a binary representation is assumed, and negative numbers are represented in a variant of 2's complement which gives the illusion of an infinite string of sign bits extending to the left.
Booleans
These represent the truth values False and True. The two objects representing the values False and True are the only Boolean objects. The Boolean type is a subtype of plain integers, and Boolean values behave like the values 0 and 1, respectively, in almost all contexts, the exception being that when converted to a string, the strings "False" or "True" are returned, respectively.
The rules for integer representation are intended to give the most meaningful interpretation of shift and mask operations involving negative integers and the least surprises when switching between the plain and long integer domains. Any operation except left shift, if it yields a result in the plain integer domain without causing overflow, will yield the same result in the long integer domain or when using mixed operands.
这里有说明
另外
Py_LOCAL_INLINE(int)
formatint(char *buf, size_t buflen, int flags,
int prec, int type, PyObject *v)
{
/* fmt = '%#.' + `prec` + 'l' + `type`
worst case length = 3 + 19 (worst len of INT_MAX on 64-bit machine)
+ 1 + 1 = 24 */
char fmt[64]; /* plenty big enough! */
char *sign;
long x;
x = PyInt_AsLong(v);
if (x == -1 && PyErr_Occurred()) {
PyErr_SetString(PyExc_TypeError, "int argument required");
return -1;
}
if (x < 0 && type == 'u') {
type = 'd';
}
if (x < 0 && (type == 'x' || type == 'X' || type == 'o'))
sign = "-";
else
sign = "";这里大概是这个意思
