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Does Python have a char type?

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Jul 02, 2019 am 09:31 AM

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Does Python have a char type?

#Python does not have a char type, and a character is also a string.

Why is there no special char data type in Python?

Simple is better than complex. In Python, the space occupied by each character in the string is 8 bits.

>>> import sys
>>> sys.getsizeof(&#39;&#39;)
37
>>> sys.getsizeof(&#39;a&#39;)
38

As you can see, the null character occupies 37 bytes, and the length The string 'a' with a value of 1 occupies 38 bytes of memory. With one more character a, there is one more byte.

Inside Python, the string is implemented like this

typedef struct {
PyObject_VAR_HEAD
long ob_shash;
int ob_sstate;
char ob_sval[1];
/* Invariants:
* ob_sval contains space for &#39;ob_size+1&#39; elements.
* ob_sval[ob_size] == 0.
* ob_shash is the hash of the string or -1 if not computed yet.
* ob_sstate != 0 iff the string object is in stringobject.c&#39;s
* &#39;interned&#39; dictionary; in this case the two references
* from &#39;interned&#39; to this object are *not counted* in ob_refcnt.
*/
} PyStringObject;

Each char is stored in ob_sval, accounting for 8 bits in size. The remaining 36 bytes mainly come from the macro PyObject_VAR_HEAD. In fact, python's string implementation also uses a global variable called *interned, which can store the length. A string of 0 or 1, that is, char, can save space and speed up.

/* This dictionary holds all interned strings. Note that references to
strings in this dictionary are *not* counted in the string&#39;s ob_refcnt.
When the interned string reaches a refcnt of 0 the string deallocation
function will delete the reference from this dictionary.
Another way to look at this is that to say that the actual reference
count of a string is: s->ob_refcnt + (s->ob_sstate?2:0)
*/
static PyObject *interned;

In fact, there are neither pointers nor "nakedness" in Python "data structure" (non-object), even the simplest integer integer is implemented in this way

typedef struct {
PyObject_HEAD
long ob_ival;
} PyIntObject;

In short, this design satisfies python's "everything "It is an object" and the design philosophy is "everything should be as simple as possible".

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