๐Ÿงธ ๊ฐ์ฒด์ง€ํ–ฅ C์–ธ์–ด

gomjellieยท2020๋…„ 5์›” 26์ผ
8
post-thumbnail

์งฑ์งฑ ํŽธํ•œ ๋‹ค๋ฅธ ๊ฐ์ฒด์ง€ํ–ฅ ์–ธ์–ด ํ•˜๋‹ค๊ฐ€ C์–ธ์–ด๋กœ ๋„˜์–ด์˜ค๋ฉด ๋ถˆํŽธํ•œ๊ฒŒ ํ•œ๋‘๊ฐœ๊ฐ€ ์•„๋‹ˆ๋‹ค.
๋ถˆํŽธํ•œ๊ฑฐ ๋‚˜์—ดํ•˜๋ผ๊ณ  ํ•˜๋ฉด ํ•œ๋„๋๋„ ์—†์ง€๋งŒ ์ œ์ผ ๋ถˆํŽธํ•œ๊ฑด class์˜ ๋ถ€์žฌ๋‹ค.

๋ญ์•ผ ๋‚ด ๊ฐ์ฒด์ง€ํ–ฅ ๋Œ๋ ค์ค˜์š”

C์–ธ์–ด๋Š” ๊ฐ์ฒด์ง€ํ–ฅ ์–ธ์–ด๊ฐ€ ์•„๋‹ˆ๋‹ค. ํ•˜์ง€๋งŒ ๊ฐ์ฒด์ง€ํ–ฅ์€ ํ”„๋กœ๊ทธ๋ž˜๋ฐ ํŒจ๋Ÿฌ๋‹ค์ž„์ผ ๋ฟ์ด๋‹ค ๊ฐ์ฒด์ง€ํ–ฅ์–ธ์–ด๊ฐ€ ์•„๋‹ˆ๋”๋ผ๋„ ๋ถˆํŽธํ•˜์ง€๋งŒ ๊ฐ์ฒด์ง€ํ–ฅ์„ ์ ์šฉํ•  ์ˆ˜ ์žˆ๋‹ค. ๋ฆฌ๋ˆ…์Šค ์ปค๋„์ด๋‚˜ GTK+์€ C์—์„œ๋„ ๊ฐ์ฒด์ง€ํ–ฅ์ด ๊ฐ€๋Šฅํ•˜๋‹ค๋Š” ๊ฒƒ์„ ๋ณด์—ฌ์ฃผ๋Š” ์ข‹์€ ์˜ˆ์‹œ์ผ ๊ฒƒ์ด๋‹ค.

์˜ค๋Š˜์€ C์–ธ์–ด์—์„œ ์ตœ๋Œ€ํ•œ ๊ฐ์ฒด์ง€ํ–ฅ ํŒจ๋Ÿฌ๋‹ค์ž„์„ ์ ์šฉ์‹œ์ผœ์„œ ๊ฐ์ฒด์ง€ํ–ฅ ์–ธ์–ด๋ฅผ ํ‰๋‚ด๋‚ด๋Š” ๋ฒ•์—๋Œ€ํ•ด์„œ ์•Œ์•„๋ณด๋ ค๊ณ ํ•œ๋‹ค.

๋œป์ด์žˆ์œผ๋ฉด ๊ธธ์ด์žˆ๋Š”๋ฒ•

์–ด์ฉŒ๋ฉด ๊ทธ ๋ชจ์Šต์ด ์œ„์—์žˆ๋Š” converter์˜ converter์˜ converter๊ฐ™์€ ํ˜ผ์ข…์˜ ๋ชจ์Šต์œผ๋กœ ๋ณด์ผ์ง€ ๋ชจ๋ฅด๊ฒ ๋‹ค... ์•„๋ฌดํŠผ ์•Œ์•„๋ณด์ž.

malloc engineering

ํ•™๊ต์—์„œ ๊ณผ์ œํ• ๋•Œ ๋ณด๋ฉด ๊ต์ˆ˜๋‹˜์ด ์–ธ์–ด ์•„๋ฌด๊ฑฐ๋‚˜ ์จ๋„ ๋œ๋‹ค๊ณ  ํ•˜๋Š”๋ฐ ๊ตณ์ด~ ๊ทธ๊ฑธ c์–ธ์–ด ์จ์„œ ๊ตฌํ˜„ํ•˜๋Š” ์‚ฌ๋žŒ๋“ค์ด ์žˆ๋‹ค. ์šฐ๋ฆฌ๋Š” ๊ทธ๋“ค์„ malloc engineer๋ผ๊ณ  ๋ถ€๋ฅธ๋‹ค.

C์–ธ์–ด๋กœ ๊ฐ์ฒด์ง€ํ–ฅ์„ ํ‰๋‚ด๋‚ด๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ž ์‹œ ์šฐ๋ฆฌ๋„ malloc engineer๊ฐ€ ๋˜์–ด์•ผ ํ•  ํ•„์š”๊ฐ€ ์žˆ๋‹ค. ์™œ ๊ทธ๋“ค์ด malloc์— ์žก์•„๋จนํžŒ ๊ดด๋ฌผ์ด ๋˜์—ˆ๋Š”์ง€, ๊ทธ๋“ค์˜ ๋จธ๋ฆฟ์†์€ ์–ด๋–ป๊ฒŒ ์ƒ๊ฒผ๋Š”์ง€ ์˜ค๋Š˜ ํ•จ๊ป˜ ์•Œ์•„๋ณด์ž.

์ƒ์„ฑ์ž

์ด์ „ ํฌ์ŠคํŒ…์—์„œ ๋งŒ๋“ค์—ˆ๋˜ ํ•™์ƒ ๊ตฌ์กฐ์ฒด๋ฅผ ์ƒ๊ฐํ•ด๋ณด์ž.

struct student {
    char* name;       // ์ด๋ฆ„
    char* major;      // ์ „๊ณต
    float gpa;        // ํ•™์ 
};

์ƒˆ๋กœ์šด ํ•™์ƒ์„ ํ•˜๋‚˜ ๋งŒ๋“ค๊ธฐ ์œ„ํ•ด์„œ ์šฐ๋ฆฌ๋Š” ์•„๋ž˜์™€ ๊ฐ™์€ ์ž‘์—…์„ ํ–ˆ๋‹ค.

struct student t = {
    .name = "Jacky",
    .major = "CSE",
    .gpa = 4.4,
};

ํ•œ๋ฒˆ ์œ„์˜ ๋ฐฉ์‹์„ ๋‹ค๋ฅธ ๊ฐ์ฒด์ง€ํ–ฅ ์–ธ์–ด์—์„œ ํ–ˆ๋˜ ๊ฒƒ์ฒ˜๋Ÿผ ์•„๋ž˜์˜ ์ƒ์„ฑ๋ฐฉ์‹์œผ๋กœ ํ•  ์ˆ˜ ์žˆ๊ฒŒ ๋งŒ๋“ค์–ด๋ณด์ž.

Student jacky = new Student("Jacky", "CSE", 4.4);

์šฐ์„  ๊ฑฐ์ถ”์žฅ์Šค๋Ÿฌ์šด struct student ๋ฅผ ์—†์•ค๋‹ค.

typedef struct student student_t;

๐Ÿ’๐Ÿปโ€โ™€๏ธ FYI: typedef ์™€ #define์˜ ์ฐจ์ด์ ?
์šฐ์„ , #define์€ scope์—์„œ ์ž์œ ๋กญ์ง€๋งŒ typedef๋Š” scope์˜ ์˜ํ–ฅ์„ ๋ฐ›๋Š”๋‹ค.
๊ทธ๋ฆฌ๊ณ , #define์œผ๋กœ ์ •์˜ํ•œ ํฌ์ธํ„ฐ๋Š” ์˜ˆ์ƒ์น˜ ๋ชปํ•œ ๋™์ž‘์„ ํ•œ๋‹ค. ์•„๋ž˜์˜ ์˜ˆ์‹œ๋ฅผ ๋ณด์ž

#define student_p student_t*
student_p jack, jill;
jack์€ student_t*, jill์€ student_t
ใ…ค
typedef student_t* student_p;
student_p jack, jill;
jack๊ณผ jill ๋ชจ๋‘ student_t*
ใ…ค
#define์€ ๋‹จ์ˆœํžˆ ์ „์ฒ˜๋ฆฌ๊ธฐ๋ฅผ ํ†ตํ•ด ์น˜ํ™˜ํ•˜๊ธฐ ๋•Œ๋ฌธ์— ์ด๋Ÿฌํ•œ ๋™์ž‘์˜ ์ฐจ์ด๊ฐ€ ๋‚˜ํƒ€๋‚œ๋‹ค.
student_t *jack, *jill;ใ…คใ…คใ…ค์ด๋ ‡๊ฒŒ ํ•ด์•ผ๋˜๋Š”๋ฐ
student_t* jack, jill;ใ…คใ…คใ…คใ…ค์ด๋ ‡๊ฒŒ ๋‹จ์ˆœํ•˜๊ฒŒ ์น˜ํ™˜ํ•จ

๐Ÿ‘ฎ๐Ÿปโ€โ™€๏ธ TMI: TODO: _t์ปจ๋ฒค์…˜ ์„ค๋ช… ์—ฌ๊ธฐ์— ์ถ”๊ฐ€

student_t new_student(char* name, char* major, float gpa) {
    student_t this = {
        .name = name,
        .major = major,
        .gpa= gpa,
    };

    return this;
}

์š”๋กœ์ผ€ํ•˜๋ฉด ์ด์ œ ํ•™์ƒ์„ ๋งŒ๋“ค๋•Œ ์•„๋ž˜์ฒ˜๋Ÿผ ๋งŒ๋“ค ์ˆ˜ ์žˆ๋‹ค!

student_t jacky = new_student("Jacky", "CSE", 4.4);

๊ต‰์žฅํžˆ ๊น”๋”ํ•ด ๋ณด์ธ๋‹ค. ํ•˜์ง€๋งŒ ๋ฌธ์ œ๊ฐ€ ์žˆ๋Š”๋ฐ jacky์— ์ฃผ์†Œ๊ฐ’์„ ๋Œ€์ž…ํ•˜๋Š” ๊ฒƒ์ด ์•„๋‹ˆ๋ผ ๊ตฌ์กฐ์ฒด ๊ฐ’์„ ๋Œ€์ž…ํ•˜๊ธฐ ๋•Œ๋ฌธ์— ๋Š๋ฆฌ๋‹ค๋Š”๊ฒƒ. (student_t์˜ ์‚ฌ์ด์ฆˆ๋งŒํผ mov๊ฐ€ ๋ฐœ์ƒํ•œ๋‹ค.)

์ด๋Ÿฐ๋Š๋‚Œ... pointer๋ฅผ ์‚ฌ์šฉํ•˜๋ฉด ๋” ๋น ๋ฅด๊ฒŒ ๋ฐ”๊ฟ€ ์ˆ˜ ์žˆ๋‹ค.

์‚ฌ์‹ค C์— Call by reference, pass by reference๋ผ๋Š”๊ฒƒ์€ ์—†๋‹ค. ํ•จ์ˆ˜์— ์ฃผ์†Œ๊ฐ€ ์˜ค๊ฐ€๋Š”๊ฒƒ์€ reference์˜ ์ด๋™์ด ์•„๋‹Œ ํฌ์ธํ„ฐ ๊ฐ’์˜ ๋ณต์‚ฌ๋‹ค.

student_t* new_student(char* name, char* major, float gpa) {
    student_t this = {
        .name = name,
        .major = major,
        .gpa= gpa,
    };

    return &this;
}

๊ทธ๋ƒฅ ์ด๋ ‡๊ฒŒ ๋ฐ”๊พธ๋ฉด ํŽธํ• ๊ฑฐ๊ฐ™์€๋ฐ ์ ˆ๋Œ€๋กœ ์œ„์ฒ˜๋Ÿผ ํ•˜๋ฉด ์•ˆ๋œ๋‹ค. this๊ฐ€ stack์— ์Œ“์ธ ๋ณ€์ˆ˜์ด๊ณ  new_student()์˜ ํ˜ธ์ถœ ์ข…๋ฃŒ์‹œ์— lifetime์ด ๋๋‚˜๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. this๋Š” ์–ธ์ œ๋“  ๋ฎ์–ด ์”Œ์›Œ์งˆ ์ˆ˜ ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ์•„๋ž˜์™€ ๊ฐ™์ด malloc()์„ ์ด์šฉํ•ด์„œ stack์ด ์•„๋‹Œ heap์˜์—ญ์— ๋ฉ”๋ชจ๋ฆฌ๋ฅผ ์žก์•„์•ผํ•œ๋‹ค.

#include <stdlib.h>
#include <assert.h>

student_t* new_student(char* name, char* major, float gpa) {
    student_t* this = malloc(sizeof(student_t));
    assert(this);

    this->name = name;
    this->major = major;
    this->gpa = gpa;

    return this;
}

// Usage
student_t* jacky = new_student("Jacky", "CSE", 4.4);

๐Ÿ’๐Ÿปโ€โ™€๏ธ FYI: malloc() ์œผ๋กœ ํ• ๋‹น๋ฐ›์€ ๊ณต๊ฐ„์„ ์™œ (student_t *)๋กœ ์บ์ŠคํŒ…ํ•˜์ง€ ์•Š๋Š”๊ฐ€?
c++์—์„œ๋Š” ์บ์ŠคํŒ…์ด ๋ฐ˜๋“œ์‹œ ํ•„์š”ํ•˜๊ธฐ ๋•Œ๋ฌธ์— c++ ํ˜ธํ™˜์„ ์œ„ํ•ด์„œ๋Š” ํ•„์š”ํ•˜์ง€๋งŒ ANSI/ISO C ํ‘œ์ค€์—์„œ ์ด๋Ÿฌํ•œ ์บ์ŠคํŒ…์€ ์ „ํ˜€ ํ•„์š”ํ•˜์ง€ ์•Š๋‹ค. g++๊ณผ gcc๋กœ ๊ฐ๊ฐ ์ปดํŒŒ์ผ ํ•ด๋ณด๋ฉด ์•Œ ์ˆ˜ ์žˆ๋‹ค.

๐Ÿฏ ๊ฟ€ํŒ: ์•Œ์•„๋‘๋ฉด ์ข‹์€ assert()
assert(this);๋Š” this๊ฐ€ 0์ด ์•„๋‹ˆ๋ฉด ์กฐ์šฉํžˆ ์ง€๋‚˜๊ฐ€๊ณ  0์ด๋ฉด ์ข…๋ฃŒํ•œ๋‹ค.
malloc()ํ•จ์ˆ˜๊ฐ€ ๊ณต๊ฐ„์„ ๋ฐ›์•„์˜ค๋Š”๋ฐ ์‹คํŒจํ•˜๋ฉด NULL์„ ๋ฆฌํ„ดํ•˜๊ธฐ ๋•Œ๋ฌธ์— ์“ด ์ฝ”๋“œ๋‹ค.
NULL ์€ (void *)0 ์œผ๋กœ stddef.h์— ์ •์˜๋˜์–ด ์žˆ๋‹ค.
์‚ฌ์‹ค assert๋Š” ํ”„๋กœ๊ทธ๋žจ์„ ๊ฐ•์ œ์ข…๋ฃŒํ•˜๊ธฐ ๋•Œ๋ฌธ์— ๋ฐฐํฌ ํ”„๋กœ๊ทธ๋žจ์—์„œ malloc()๊ณผ ๊ฐ™์ด ์“ฐ๋Š” ์ผ์€ ์—†์–ด์•ผ ํ•  ๊ฒƒ์ด๋‹ค.

์‹ฑ๊ธ€ํ†ค ํŒจํ„ด

์‹ฑ๊ธ€ํ†ค ํŒจํ„ด์€ ๋‹จ ํ•˜๋‚˜์˜ ๊ฐ์ฒด๋งŒ์„ ์ƒ์„ฑํ•˜๋Š” ๋””์ž์ธํŒจํ„ด์ด๋‹ค. C์—์„œ๋Š” ํ•จ์ˆ˜์† static ๋ณ€์ˆ˜๋ฅผ ์ด์šฉํ•ด์„œ ๊ตฌํ˜„ํ•  ์ˆ˜ ์žˆ๋‹ค.

student_t* new_student(char* name, char* major, float gpa) {
    static student_t this;
    static bool is_initialized;
    
    if (is_initialized) return &this;
    this = (student_t) {
        .name = name,
        .major = major,
        .gpa = gpa,
    };
    is_initialized = true;

    return &this;
}

this๋Š” ๋‹จ ํ•œ๋ฒˆ๋งŒ ์ดˆ๊ธฐํ™”๋˜๊ณ  new_student๋ฅผ ๊ณ„์† ํ˜ธ์ถœํ•ด๋„ ๊ฐ™์€ &this๋ฅผ ๋ฆฌํ„ดํ•œ๋‹ค.

๐Ÿ‘€ : ์•„๊นŒ๋Š” ํ•จ์ˆ˜ ๋‚ด๋ถ€ ๋ณ€์ˆ˜ &this ๋ฆฌํ„ดํ•˜์ง€ ๋ง๋ผ๊ณ  ํ•˜์ง€์•Š์•˜์—ˆ๋ƒ?
Answer : ํ•จ์ˆ˜ ๋‚ด๋ถ€์— static์œผ๋กœ ์„ ์–ธ๋œ ๋ณ€์ˆ˜๋Š” stack์— ์Œ“์ด์ง€ ์•Š๊ณ  .bss ์˜์—ญ์— ์ž๋ฆฌ์žก๋Š”๋‹ค. ๋”ฐ๋ผ์„œ ๋ฎ์–ด ์”Œ์›Œ์งˆ ์ผ์ด ์—†๊ธฐ๋•Œ๋ฌธ์— static ๋ณ€์ˆ˜์˜ ์ฃผ์†Œ๋ฅผ ๋ฆฌํ„ดํ•˜๋Š”๊ฒƒ์€ ํ•ฉ๋ฒ•์ ์ด๋‹ค. ์ž์„ธํ•œ ๋‚ด์šฉ์€ runtime storageํŽธ ์ฐธ๊ณ .

๐Ÿ‘€ static bool is_initialized ์ด๊ฑฐ ์ดˆ๊ธฐํ™” ์•ˆํ•ด์ค˜๋„ ๋˜๋Š”๊ฑฐ๋ƒ?
Answer : .bss์˜์—ญ์— ์ž๋ฆฌํ•˜๋Š” static ๋ณ€์ˆ˜๋“ค, ์ „์—ญ๋ณ€์ˆ˜๋“ค์€ ๋”ฐ๋กœ ์ดˆ๊ธฐํ™”๋ฅผ ํ•˜์ง€ ์•Š์„๋•Œ 0์œผ๋กœ ์ดˆ๊ธฐํ™”๊ฐ€ ๋ณด์žฅ๋œ๋‹ค. (float, double๋“ฑ์€ 0.0์œผ๋กœ ์ดˆ๊ธฐํ™”ํ•ด์ค€๋‹ค)
๋”ฐ๋ผ์„œ static์œผ๋กœ is_initialized๋ฅผ ๋งŒ๋“ค์ง€ ์•Š๊ณ  ๋‚ด๋ถ€์˜ ๋ณ€์ˆ˜๊ฐ€ 0์ธ์ง€ ๋น„๊ตํ•˜๋Š”๊ฒƒ์œผ๋กœ ๊ทธ ์—ญํ• ์„ ๋Œ€์‹ ํ•ด๋„ ๋œ๋‹ค.

TODO: ์ธ์ž ์ „๋ถ€ ์•ˆ๋„˜๊ฒจ ์ฃผ๋Š”๊ฑฐ๋Š” ์–ด๋–ป๊ฒŒ ๊ตฌํ˜„ํ•˜๋ƒ์— ๊ด€ํ•œ ๋‚ด์šฉ ์—ฌ๊ธฐ์—

TODO: ์ธ์ž ๊ธฐ๋ณธ๊ฐ’ ์„ค์ • ์—ฌ๊ธฐ์— (๊น€์ค€์ฒ )

์†Œ๋ฉธ์ž

์†Œ๋ฉธ์ž์˜ ์ฑ…์ž„

์†Œ๋ฉธ์ž์•ˆ์—์„œ๋Š” ๊ตฌ์กฐ์ฒด ๋ฉค๋ฒ„๋“ค๋„ ํ•จ๊ป˜ ์†Œ๋ฉธ์‹œ์ผœ์•ผ ํ•  ์ฑ…์ž„์ด ์žˆ๋‹ค. ๋ฉค๋ฒ„๊ฐ€ ๋™์ ํ• ๋‹น๋œ ๋ฉ”๋ชจ๋ฆฌ๋ฅผ ๊ฐ–๊ณ ์žˆ๋‹ค๋ฉด this๋ฅผ ์†Œ๋ฉธ์‹œํ‚ค๊ธฐ ์ „์— ๋จผ์ € ๋ฉค๋ฒ„๋“ค์„ ์ •๋ฆฌ์‹œ์ผœ์ค˜์•ผํ•œ๋‹ค. ์—ฌ๊ธฐ์„œ๋Š” name๊ณผ major๊ฐ€ string literal์„ ๊ฐ€๋ฅดํ‚ค๊ธฐ๋•Œ๋ฌธ์— ๊ทธ๋ƒฅ this๋งŒ ์ •๋ฆฌํ•ด์ฃผ๋ฉด ๋œ๋‹ค.

์†Œ๋ฉธ์ž ๊ธฐ๋Šฅ์„ ํ•จ์ˆ˜๋กœ ๋งŒ๋“ค์–ด๋ณด์ž.

void del_student(student* this) {
    free(this);
}
// Usage
student_t jacky = new_student(...);
del_student(jacky);

๐Ÿ‘ฎ๐Ÿปโ€โ™€๏ธ TMI: ๋ณดํ†ต destructor, destroyer, del ๋“ฑ์˜ ๋ช…์นญ์„ ์“ด๋‹ค. ์ทจํ–ฅ์— ๋”ฐ๋ผ์„œ ์•ž์— ๋ถ™์ผ์ง€ ๋’ค์— ๋ถ™์ผ์ง€ ๋‹ค๋ฆ„ del_student, student_del ์ด๋Ÿฐ์‹์œผ๋กœ

๋งŒ์•ฝ์— name๊ณผ major๊ฐ€ string literal์ด ์•„๋‹Œ ๋™์ ํ• ๋‹น๋œ ์˜์—ญ์„ ๊ฐ€๋ฆฌํ‚ค๋Š” ๊ฒฝ์šฐ๋Š” ์ƒ์„ฑ์ž์™€ ์†Œ๋ฉธ์ž๊ฐ€ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ๋‹ฌ๋ผ์ง„๋‹ค.

#include <string.h>

student_t* new_student(char* name, char* major, float gpa) {
    student_t* this = malloc(sizeof(student_t));
    
    this->name = strdup(name);
    this->major = strdup(major);
    this->gpa = gpa;
    
    return this;
}

void del_student(student* this) {
    free(this->name);
    free(this->major);
    free(this);
}

๐Ÿฏ ๊ฟ€ํŒ: strdup()๋Š” new_string()๊ฐ™์€ ์—ญํ• ์„ ํ•œ๋‹ค. ์ŠคํŠธ๋ง์„ ๋™์ ํ• ๋‹น๋œ ๊ณต๊ฐ„์— ๋‹ด์•„์„œ ๊ทธ ์ฃผ์†Œ๊ฐ’์„ ๋ฆฌํ„ดํ•ด์ค€๋‹ค. heap์— ๋™์ ํ• ๋‹น๋œ ์ฃผ์†Œ๊ธฐ ๋•Œ๋ฌธ์— ๋‚˜์ค‘์— free() ํ•ด์ค˜์•ผ ํ•  ์˜๋ฌด๊ฐ€์žˆ๋‹ค.

reference

profile
ํœดํ•™์ค‘๋…์ž ์˜ค์ธ๊ทœ

2๊ฐœ์˜ ๋Œ“๊ธ€

comment-user-thumbnail
2020๋…„ 5์›” 26์ผ

๊ธ€ ์ž˜ ์ฝ์—ˆ์Šต๋‹ˆ๋‹ค.
'ํ•˜์ง€๋งŒ ๋œป์ด์žˆ์œผ๋ฉด ๊ธธ์ด์žˆ๋Š”๋ฒ•' ์ด ๋ฌธ์žฅ์ด ์ œ ์‹ฌ๊ธˆ์„ ์šธ๋ฆฌ๋„ค์š”

์•ž์œผ๋กœ๋„ ์ข‹์€ ๊ธ€ ๋ถ€ํƒ๋“œ๋ฆฝ๋‹ˆ๋‹ค. :)

1๊ฐœ์˜ ๋‹ต๊ธ€