1、A thesis submitted toin partial fulfillment of the requirementfor the degree ofMaster of EngineeringC語(yǔ)言詳解 - 枚舉類型注：以下全部代碼的執(zhí)行環(huán)境為VC+ 6.0在程序中，可能需要為某些整數(shù)定義一個(gè)別名，我們可以利用預(yù)處理指令#define來(lái)完成這項(xiàng)工作，您的代碼可能是：#define MON 1#define TUE 2#define WED 3#define THU 4#define FRI 5#define SAT 6#define SUN 7在此，我們定義一種新的數(shù)據(jù)類型，希望它能完

2、成同樣的工作。這種新的數(shù)據(jù)類型叫枚舉型。1. 定義一種新的數(shù)據(jù)類型 - 枚舉型 以下代碼定義了這種新的數(shù)據(jù)類型 - 枚舉型enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN;(1) 枚舉型是一個(gè)集合，集合中的元素(枚舉成員)是一些命名的整型常量，元素之間用逗號(hào),隔開。(2) DAY是一個(gè)標(biāo)識(shí)符，可以看成這個(gè)集合的名字，是一個(gè)可選項(xiàng)，即是可有可無(wú)的項(xiàng)。(3) 第一個(gè)枚舉成員的默認(rèn)值為整型的0，后續(xù)枚舉成員的值在前一個(gè)成員上加1。(4) 可以人為設(shè)定枚舉成員的值，從而自定義某個(gè)范圍內(nèi)的整數(shù)。(5) 枚舉型是預(yù)處理指令#define的替代。(6) 類型定義以分號(hào)

3、;結(jié)束。2. 使用枚舉類型對(duì)變量進(jìn)行聲明新的數(shù)據(jù)類型定義完成后，它就可以使用了。我們已經(jīng)見過(guò)最基本的數(shù)據(jù)類型，如：整型int, 單精度浮點(diǎn)型float, 雙精度浮點(diǎn)型double, 字符型char, 短整型short等等。用這些基本數(shù)據(jù)類型聲明變量通常是這樣：char a; /變量a的類型均為字符型charchar letter;int x, y, z; /變量x,y和z的類型均為整型intint number;double m, n;double result; /變量result的類型為雙精度浮點(diǎn)型double既然枚舉也是一種數(shù)據(jù)類型，那么它和基本數(shù)據(jù)類型一樣也可以對(duì)變量進(jìn)行聲明。方法一：

4、枚舉類型的定義和變量的聲明分開enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN;enum DAY yesterday;enum DAY today;enum DAY tomorrow; /變量tomorrow的類型為枚舉型enum DAYenum DAY good_day, bad_day; /變量good_day和bad_day的類型均為枚舉型enum DAY方法二：類型定義與變量聲明同時(shí)進(jìn)行：enum /跟第一個(gè)定義不同的是，此處的標(biāo)號(hào)DAY省略，這是允許的。 saturday, sunday = 0, monday, tuesday, wednes

5、day, thursday, friday workday; /變量workday的類型為枚舉型enum DAYenum week Mon=1, Tue, Wed, Thu, Fri Sat, Sun days; /變量days的類型為枚舉型enum weekenum BOOLEAN false, true end_flag, match_flag; /定義枚舉類型并聲明了兩個(gè)枚舉型變量方法三：用typedef關(guān)鍵字將枚舉類型定義成別名，并利用該別名進(jìn)行變量聲明：typedef enum workday saturday, sunday = 0, monday, tuesday, wednes

6、day, thursday, friday workday; /此處的workday為枚舉型enum workday的別名workday today, tomorrow; /變量today和tomorrow的類型為枚舉型workday，也即enum workdayenum workday中的workday可以省略：typedef enum saturday, sunday = 0, monday, tuesday, wednesday, thursday, friday workday; /此處的workday為枚舉型enum workday的別名workday today, tomorrow

7、; /變量today和tomorrow的類型為枚舉型workday，也即enum workday也可以用這種方式：typedef enum workday saturday, sunday = 0, monday, tuesday, wednesday, thursday, friday;workday today, tomorrow; /變量today和tomorrow的類型為枚舉型workday，也即enum workday注意：同一個(gè)程序中不能定義同名的枚舉類型，不同的枚舉類型中也不能存在同名的命名常量。錯(cuò)誤示例如下所示：錯(cuò)誤聲明一：存在同名的枚舉類型typedef enum wedne

8、sday, thursday, friday workday;typedef enum WEEK saturday, sunday = 0, monday, workday; 錯(cuò)誤聲明二：存在同名的枚舉成員typedef enum wednesday, thursday, friday workday_1;typedef enum WEEK wednesday, sunday = 0, monday, workday_2;3. 使用枚舉類型的變量3.1 對(duì)枚舉型的變量賦值。實(shí)例將枚舉類型的賦值與基本數(shù)據(jù)類型的賦值進(jìn)行了對(duì)比：方法一：先聲明變量，再對(duì)變量賦值#include/* 定義枚舉類型 *

9、/enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN ;void main() /* 使用基本數(shù)據(jù)類型聲明變量，然后對(duì)變量賦值 */ int x, y, z; x = 10; y = 20; z = 30; /* 使用枚舉類型聲明變量，再對(duì)枚舉型變量賦值 */ enum DAY yesterday, today, tomorrow; yesterday = MON; today = TUE; tomorrow = WED; printf(%d %d %d n, yesterday, today, tomorrow);方法二：聲明變量的同時(shí)賦初值#inclu

10、de /* 定義枚舉類型 */enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN ;void main() /* 使用基本數(shù)據(jù)類型聲明變量同時(shí)對(duì)變量賦初值 */ int x=10, y=20, z=30; /* 使用枚舉類型聲明變量同時(shí)對(duì)枚舉型變量賦初值 */ enum DAY yesterday = MON, today = TUE, tomorrow = WED; printf(%d %d %d n, yesterday, today, tomorrow);方法三：定義類型的同時(shí)聲明變量，然后對(duì)變量賦值。#include /* 定義枚舉類型，同時(shí)聲明該

11、類型的三個(gè)變量，它們都為全局變量 */enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN yesterday, today, tomorrow;/* 定義三個(gè)具有基本數(shù)據(jù)類型的變量，它們都為全局變量 */int x, y, z;void main() /* 對(duì)基本數(shù)據(jù)類型的變量賦值 */ x = 10; y = 20; z = 30; /* 對(duì)枚舉型的變量賦值 */ yesterday = MON; today = TUE; tomorrow = WED; printf(%d %d %d n, x, y, z); /輸出：10 20 30 printf(%

12、d %d %d n, yesterday, today, tomorrow); /輸出：1 2 3方法四：類型定義，變量聲明，賦初值同時(shí)進(jìn)行。#include /* 定義枚舉類型，同時(shí)聲明該類型的三個(gè)變量，并賦初值。它們都為全局變量 */enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN yesterday = MON, today = TUE, tomorrow = WED;/* 定義三個(gè)具有基本數(shù)據(jù)類型的變量，并賦初值。它們都為全局變量 */int x = 10, y = 20, z = 30;void main() printf(%d %d %d n

13、, x, y, z); /輸出：10 20 30 printf(%d %d %d n, yesterday, today, tomorrow); /輸出：1 2 33.2 對(duì)枚舉型的變量賦整數(shù)值時(shí)，需要進(jìn)行類型轉(zhuǎn)換。#include enum DAY MON=1, TUE, WED, THU, FRI, SAT, SUN ;void main() enum DAY yesterday, today, tomorrow; yesterday = TUE; today = (enum DAY) (yesterday + 1); /類型轉(zhuǎn)換 tomorrow = (enum DAY) 30; /類型

14、轉(zhuǎn)換 /tomorrow = 3; /錯(cuò)誤 printf(%d %d %d n, yesterday, today, tomorrow); /輸出：2 3 303.3 使用枚舉型變量#includeenum BELL = a, BACKSPACE = b, HTAB = t, RETURN = r, NEWLINE = n, 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; c

15、har str = Im Ely efod; match_flag = FALSE; for(; strindex != 0; index+) if( SPACE != strindex ) 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, N

16、EWLINE, RETURN);輸出：match 2 timescount of letters: 10Press any key to continue4. 枚舉類型與sizeof運(yùn)算符#include enum escapes BELL = a, BACKSPACE = b, HTAB = t, RETURN = r, NEWLINE = n, VTAB = v, SPACE = ;enum BOOLEAN FALSE = 0, TRUE match_flag;void main() printf(%d bytes n, sizeof(enum escapes); /4 bytes pri

17、ntf(%d bytes n, sizeof(escapes); /4 bytes printf(%d bytes n, sizeof(enum BOOLEAN); /4 bytes printf(%d bytes n, sizeof(BOOLEAN); /4 bytes printf(%d bytes n, sizeof(match_flag); /4 bytes printf(%d bytes n, sizeof(SPACE); /4 bytes printf(%d bytes n, sizeof(NEWLINE); /4 bytes printf(%d bytes n, sizeof(F

18、ALSE); /4 bytes printf(%d bytes n, sizeof(0); /4 bytes5. 綜合舉例#includeenum Season spring, summer=100, fall=96, winter;typedef enum Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, SundayWeekday;void main() /* Season */ printf(%d n, spring); / 0 printf(%d, %c n, summer, summer); / 100, d printf(%d n, fall+winter); / 193 Season mySeason=winter; if(winter=mySeason) printf(mySeason is winter n); / mySeason is winter int x=100; if(x=summer) printf(x is equal to summern); / x is equal to summer printf(%d bytesn, s