不明なsizeof(enum)データ構造ストレージの問題
62506 ワード
sizeof(enum)
typedef struct weekday_st { enum week {sun=123456789,mon,tue,wed,thu,fri,sat,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,aa,ab,ac,ad,ae,af,ag,ah,ai,aj,ak}; enum day{monring, moon, aftermoon}; }weekday_st; int main(int argc, char *argv[]) { printf("sizeof(weekday_st)=%d
", sizeof(weekday_st)); printf("sizeof(weekday)=%d
", sizeof(weekday_st::week)); printf("sizeof(day)=%d
", sizeof(weekday_st::day)); return 0; } sizeof(weekday_st)=1 sizeof(weekday)=4 sizeof(day)=4 sizeof 1， enum ， ， 4 ？
emum 4
emum
2 emum
enum ，
printf("sizeof(weekday_st)=%d
", sizeof(weekday_st));
， sizeof 0
sizeof
PC char
sizeof 1
printf("sizeof(weekday)=%d
", sizeof(weekday_st::week));
printf("sizeof(day)=%d
", sizeof(weekday_st::day));
sizeof 4
， ，enum int
enum int ， int * ， enum ， sizeof 4， 。
typedef struct weekday_st
{
enum week {sun=123456789,mon,tue,wed,thu,fri,sat,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,aa,ab,ac,ad,ae,af,ag,ah,ai,aj,ak};
enum day{monring, moon, aftermoon};
}weekday_st;
-----------------------------------------------------------------------------------
enum week enum day “ ”， ， ：
typedef struct weekday_st
{
enum week {sun=123456789,mon,tue,wed,thu,fri,sat,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,aa,ab,ac,ad,ae,af,ag,ah,ai,aj,ak} ew;
enum day{monring, moon, aftermoon} ed;
}weekday_st;
sizeof ， 8 。
， 8 ， sizeof(week)， week 4， ？
enum ... UINT ...
， ， 。
enum ， “ ”。
struct 。
enum week ed; ed.mon 。
C++ Primer : enum , .: int,unsigned int,long ,unsigned long, ,sizeof(enum) 4
列挙体変数とそのメンバー定数のサイズについて(sizeof)
#include <stdio.h>
int main()
{
enum foo{};
enum gender{male, female};
enum season{spring, summer, autumn, winter};
enum week{sunday, monday, tuesday, wednesday, thursday, friday, saturday};
printf("%d
",sizeof(enum));// ？ 4
printf("%d
",sizeof(foo));// 4
printf("%d
",sizeof(gender));// 4
printf("%d
",sizeof(season));// 4
printf("%d
",sizeof(week));// 4
printf("%d
",sizeof(male));// 4
return 0;
} Visual C++ 6.0 。 4 ？
説明:列挙型は、前処理命令defineの代替である.列挙型は集合であり、集合内の要素(列挙メンバー)はいくつかの命名された整数定数であり、要素間はカンマで区切られている.タイプ定義はセミコロンです.終わります.最初の列挙メンバーのデフォルト値は整数の0で、後続の列挙メンバーの値は前のメンバーに1を加えます.
連発科の筆記試験問題:
#include
using namespace std;
enum value
value1,
value3=0,
value5,
{
cout<
if(i<4)
break;
列挙とsizeof
#include
enum WEEK
sat=2,
mon=11,
};
int main(void)
printf("%d %d %d",sun,tue,sizeof(tue)); //3 12 4
return 0;
#include
enum
BELL = '\a',
HTAB = '\t',
NEWLINE = '',
SPACE = ' '
enum BOOLEAN { FALSE = 0, TRUE } match_flag;
void main()
{
int index = 0;
int count_of_space = 0;
char str[] = "I'm Ely efod";
match_flag = FALSE;
for(; str[index] != '\0'; index++)
count_of_letter++;
{
count_of_space++;
printf("count of letters: %d %c%c", count_of_letter, NEWLINE, RETURN);
struct A
{
enum day{monring, moon, aftermoon};
};
sizeof(A) //1
sizeof(A::day) //4
struct A{
enum day{monring, moon, aftermoon} today;
};
sizeof(A)， 4 ，enum day{monring, moon, aftermoon}; enum ， ， struct A ， 1
：
sizeof(A) // 1
sizeof(A::day) // day
day， 。
enum day ， 。 。
，sizeof(A), ，
C int，
sizeof(A::day) 4.
C -
： VC++ 6.0
， ， #define ， ：
#define MON 1
#define TUE 2
#define WED 3
#define THU 4
#define FRI 5
#define SAT 6
#define SUN 7
， ， 。 。
1. -
-
enum DAY
{
MON=1, TUE, WED, THU, FRI, SAT, SUN
};
(1) ， ( ) ， , 。
(2) DAY ， ， ， 。
(3) 0， 1。
(4) ， 。
(5) #define 。
(6) ; 。
2.
， 。 ， ： int, float, double, char, short 。 ：
char a; // a char
char letter;
int x,
y,
z; // x,y z int
int number;
double m, n;
double result; // result double
， 。
：
enum DAY
{
MON=1, TUE, WED, THU, FRI, SAT, SUN
};
enum DAY yesterday;
enum DAY today;
enum DAY tomorrow; // tomorrow enum DAY
enum DAY good_day, bad_day; // good_day bad_day enum DAY
： ：
enum // ， DAY ， 。
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
} workday; // workday enum DAY
enum week { Mon=1, Tue, Wed, Thu, Fri Sat, Sun} days; // days enum week
enum BOOLEAN { false, true } end_flag, match_flag; //
： typedef ， ：
typedef enum workday
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
} workday; // workday enum workday
workday today, tomorrow; // today tomorrow workday， enum workday
enum workday workday ：
typedef enum
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
} workday; // workday enum workday
workday today, tomorrow; // today tomorrow workday， enum workday
：
typedef enum workday
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
};
workday today, tomorrow; // today tomorrow workday， enum workday
： ， 。 ：
：
typedef enum
{
wednesday,
thursday,
friday
} workday;
typedef enum WEEK
{
saturday,
sunday = 0,
monday,
} workday;
：
typedef enum
{
wednesday,
thursday,
friday
} workday_1;
typedef enum WEEK
{
wednesday,
sunday = 0,
monday,
} workday_2;
3.
3.1 。
：
： ，
#include<stdio.h>
/* */
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN };
void main()
{
/* ， */
int x, y, z;
x = 10;
y = 20;
z = 30;
/* ， */
enum DAY yesterday, today, tomorrow;
yesterday = MON;
today = TUE;
tomorrow = WED;
printf("%d %d %d
", yesterday, today, tomorrow);
}
：
#include <stdio.h>
/* */
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN };
void main()
{
/* */
int x=10, y=20, z=30;
/* */
enum DAY yesterday = MON,
today = TUE,
tomorrow = WED;
printf("%d %d %d
", yesterday, today, tomorrow);
}
： ， 。
#include <stdio.h>
/* ， ， */
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN } yesterday, today, tomorrow;
/* ， */
int x, y, z;
void main()
{
/* */
x = 10; y = 20; z = 30;
/* */
yesterday = MON;
today = TUE;
tomorrow = WED;
printf("%d %d %d
", x, y, z); // ：10 20 30
printf("%d %d %d
", yesterday, today, tomorrow); // ：1 2 3
}
： ， ， 。
#include <stdio.h>
/* ， ， 。 */
enum DAY
{
MON=1,
TUE,
WED,
THU,
FRI,
SAT,
SUN
}
yesterday = MON, today = TUE, tomorrow = WED;
/* ， 。 */
int x = 10, y = 20, z = 30;
void main()
{
printf("%d %d %d
", x, y, z); // ：10 20 30
printf("%d %d %d
", yesterday, today, tomorrow); // ：1 2 3
}
3.2 ， 。
#include <stdio.h>
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN };
void main()
{
enum DAY yesterday, today, tomorrow;
yesterday = TUE;
today = (enum DAY) (yesterday + 1); //
tomorrow = (enum DAY) 30; //
//tomorrow = 3; //
printf("%d %d %d
", yesterday, today, tomorrow); // ：2 3 30
}
3.3
#include<stdio.h>
enum
{
BELL = '\a',
BACKSPACE = '\b',
HTAB = '\t',
RETURN = '\r',
NEWLINE = '
',
VTAB = '\v',
SPACE = ' '
};
enum BOOLEAN { FALSE = 0, TRUE } match_flag;
void main()
{
int index = 0;
int count_of_letter = 0;
int count_of_space = 0;
char str[] = "I'm Ely efod";
match_flag = FALSE;
for(; str[index] != '\0'; index++)
if( SPACE != str[index] )
count_of_letter++;
else
{
match_flag = (enum BOOLEAN) 1;
count_of_space++;
}
printf("%s %d times %c", match_flag ? "match" : "not match", count_of_space, NEWLINE);
printf("count of letters: %d %c%c", count_of_letter, NEWLINE, RETURN);
}
：
match 2 times
count of letters: 10
Press any key to continue
4. sizeof
#include <stdio.h>
enum escapes
{
BELL = '\a',
BACKSPACE = '\b',
HTAB = '\t',
RETURN = '\r',
NEWLINE = '
',
VTAB = '\v',
SPACE = ' '
};
enum BOOLEAN { FALSE = 0, TRUE } match_flag;
void main()
{
printf("%d bytes
", sizeof(enum escapes)); //4 bytes
printf("%d bytes
", sizeof(escapes)); //4 bytes
printf("%d bytes
", sizeof(enum BOOLEAN)); //4 bytes
printf("%d bytes
", sizeof(BOOLEAN)); //4 bytes
printf("%d bytes
", sizeof(match_flag)); //4 bytes
printf("%d bytes
", sizeof(SPACE)); //4 bytes
printf("%d bytes
", sizeof(NEWLINE)); //4 bytes
printf("%d bytes
", sizeof(FALSE)); //4 bytes
printf("%d bytes
", sizeof(0)); //4 bytes
}
5.
#include<stdio.h>
enum Season
{
spring, summer=100, fall=96, winter
};
typedef enum
{
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday
}
Weekday;
void main()
{
/* Season */
printf("%d
", spring); // 0
printf("%d, %c
", summer, summer); // 100, d
printf("%d
", fall+winter); // 193
Season mySeason=winter;
if(winter==mySeason)
printf("mySeason is winter
"); // mySeason is winter
int x=100;
if(x==summer)
printf("x is equal to summer
"); // x is equal to summer
printf("%d bytes
", sizeof(spring)); // 4 bytes
/* Weekday */
printf("sizeof Weekday is: %d
", sizeof(Weekday)); //sizeof Weekday is: 4
Weekday today = Saturday;
Weekday tomorrow;
if(today == Monday)
tomorrow = Tuesday;
else
tomorrow = (Weekday) (today + 1); //remember to convert from int to Weekday
}C -
： VC++ 6.0
， ， #define ， ：
#define MON 1
#define TUE 2
#define WED 3
#define THU 4
#define FRI 5
#define SAT 6
#define SUN 7
， ， 。 。
1. -
-
enum DAY
{
MON=1, TUE, WED, THU, FRI, SAT, SUN
};
(1) ， ( ) ， , 。
(2) DAY ， ， ， 。
(3) 0， 1。
(4) ， 。
(5) #define 。
(6) ; 。
2.
， 。 ， ： int, float, double, char, short 。 ：
char a; // a char
char letter;
int x,
y,
z; // x,y z int
int number;
double m, n;
double result; // result double
， 。
：
enum DAY
{
MON=1, TUE, WED, THU, FRI, SAT, SUN
};
enum DAY yesterday;
enum DAY today;
enum DAY tomorrow; // tomorrow enum DAY
enum DAY good_day, bad_day; // good_day bad_day enum DAY
： ：
enum // ， DAY ， 。
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
} workday; // workday enum DAY
enum week { Mon=1, Tue, Wed, Thu, Fri Sat, Sun} days; // days enum week
enum BOOLEAN { false, true } end_flag, match_flag; //
： typedef ， ：
typedef enum workday
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
} workday; // workday enum workday
workday today, tomorrow; // today tomorrow workday， enum workday
enum workday workday ：
typedef enum
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
} workday; // workday enum workday
workday today, tomorrow; // today tomorrow workday， enum workday
：
typedef enum workday
{
saturday,
sunday = 0,
monday,
tuesday,
wednesday,
thursday,
friday
};
workday today, tomorrow; // today tomorrow workday， enum workday
： ， 。 ：
：
typedef enum
{
wednesday,
thursday,
friday
} workday;
typedef enum WEEK
{
saturday,
sunday = 0,
monday,
} workday;
：
typedef enum
{
wednesday,
thursday,
friday
} workday_1;
typedef enum WEEK
{
wednesday,
sunday = 0,
monday,
} workday_2;
3.
3.1 。
：
： ，
#include<stdio.h>
/* */
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN };
void main()
{
/* ， */
int x, y, z;
x = 10;
y = 20;
z = 30;
/* ， */
enum DAY yesterday, today, tomorrow;
yesterday = MON;
today = TUE;
tomorrow = WED;
printf("%d %d %d
", yesterday, today, tomorrow);
}
：
#include <stdio.h>
/* */
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN };
void main()
{
/* */
int x=10, y=20, z=30;
/* */
enum DAY yesterday = MON,
today = TUE,
tomorrow = WED;
printf("%d %d %d
", yesterday, today, tomorrow);
}
： ， 。
#include <stdio.h>
/* ， ， */
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN } yesterday, today, tomorrow;
/* ， */
int x, y, z;
void main()
{
/* */
x = 10; y = 20; z = 30;
/* */
yesterday = MON;
today = TUE;
tomorrow = WED;
printf("%d %d %d
", x, y, z); // ：10 20 30
printf("%d %d %d
", yesterday, today, tomorrow); // ：1 2 3
}
： ， ， 。
#include <stdio.h>
/* ， ， 。 */
enum DAY
{
MON=1,
TUE,
WED,
THU,
FRI,
SAT,
SUN
}
yesterday = MON, today = TUE, tomorrow = WED;
/* ， 。 */
int x = 10, y = 20, z = 30;
void main()
{
printf("%d %d %d
", x, y, z); // ：10 20 30
printf("%d %d %d
", yesterday, today, tomorrow); // ：1 2 3
}
3.2 ， 。
#include <stdio.h>
enum DAY { MON=1, TUE, WED, THU, FRI, SAT, SUN };
void main()
{
enum DAY yesterday, today, tomorrow;
yesterday = TUE;
today = (enum DAY) (yesterday + 1); //
tomorrow = (enum DAY) 30; //
//tomorrow = 3; //
printf("%d %d %d
", yesterday, today, tomorrow); // ：2 3 30
}
3.3
#include<stdio.h>
enum
{
BELL = '\a',
BACKSPACE = '\b',
HTAB = '\t',
RETURN = '\r',
NEWLINE = '
',
VTAB = '\v',
SPACE = ' '
};
enum BOOLEAN { FALSE = 0, TRUE } match_flag;
void main()
{
int index = 0;
int count_of_letter = 0;
int count_of_space = 0;
char str[] = "I'm Ely efod";
match_flag = FALSE;
for(; str[index] != '\0'; index++)
if( SPACE != str[index] )
count_of_letter++;
else
{
match_flag = (enum BOOLEAN) 1;
count_of_space++;
}
printf("%s %d times %c", match_flag ? "match" : "not match", count_of_space, NEWLINE);
printf("count of letters: %d %c%c", count_of_letter, NEWLINE, RETURN);
}
：
match 2 times
count of letters: 10
Press any key to continue
4. sizeof
#include <stdio.h>
enum escapes
{
BELL = '\a',
BACKSPACE = '\b',
HTAB = '\t',
RETURN = '\r',
NEWLINE = '
',
VTAB = '\v',
SPACE = ' '
};
enum BOOLEAN { FALSE = 0, TRUE } match_flag;
void main()
{
printf("%d bytes
", sizeof(enum escapes)); //4 bytes
printf("%d bytes
", sizeof(escapes)); //4 bytes
printf("%d bytes
", sizeof(enum BOOLEAN)); //4 bytes
printf("%d bytes
", sizeof(BOOLEAN)); //4 bytes
printf("%d bytes
", sizeof(match_flag)); //4 bytes
printf("%d bytes
", sizeof(SPACE)); //4 bytes
printf("%d bytes
", sizeof(NEWLINE)); //4 bytes
printf("%d bytes
", sizeof(FALSE)); //4 bytes
printf("%d bytes
", sizeof(0)); //4 bytes
}
5.
#include<stdio.h>
enum Season
{
spring, summer=100, fall=96, winter
};
typedef enum
{
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday
}
Weekday;
void main()
{
/* Season */
printf("%d
", spring); // 0
printf("%d, %c
", summer, summer); // 100, d
printf("%d
", fall+winter); // 193
Season mySeason=winter;
if(winter==mySeason)
printf("mySeason is winter
"); // mySeason is winter
int x=100;
if(x==summer)
printf("x is equal to summer
"); // x is equal to summer
printf("%d bytes
", sizeof(spring)); // 4 bytes
/* Weekday */
printf("sizeof Weekday is: %d
", sizeof(Weekday)); //sizeof Weekday is: 4
Weekday today = Saturday;
Weekday tomorrow;
if(today == Monday)
tomorrow = Tuesday;
else
tomorrow = (Weekday) (today + 1); //remember to convert from int to Weekday
}