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Chapter 10 結構 , Unions, 位元處理與列舉型別

Chapter 10 結構 , Unions, 位元處理與列舉型別. 大綱 10.1 簡介 10.2 結構定義 10.3 結構初始值設定 10.4 存取結構成員 10.5 使用結構與函數 10.6 typedef 10.7 Example: 高效率的洗牌與發牌 10.8 Unions 10.9 位元運算子 10.10 位元欄位 10.11 列舉型別常數. 10.1 簡介. 結構 聚合型的資料型態，由其他型態的元素組成，不同型態資料的集合。 彼此相關的變數結合成 ( 混合體 ) 相同的名稱 包含不同型態資料

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Chapter 10 結構 , Unions, 位元處理與列舉型別

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  1. Chapter 10 結構, Unions, 位元處理與列舉型別 大綱 10.1 簡介 10.2 結構定義 10.3 結構初始值設定 10.4 存取結構成員 10.5 使用結構與函數 10.6 typedef 10.7 Example:高效率的洗牌與發牌 10.8 Unions 10.9 位元運算子 10.10 位元欄位 10.11 列舉型別常數

  2. 10.1 簡介 • 結構 • 聚合型的資料型態，由其他型態的元素組成，不同型態資料的集合。 • 彼此相關的變數結合成 (混合體) 相同的名稱 • 包含不同型態資料 • 通常來定義儲存在檔案內的記錄(records) • 指標和結構可以構成複雜的資料結構，如： • 鏈結串列 linked lists, • 佇列 queues, • 堆疊 stacks 和 • 樹 trees

  3. 結構標籤(tag) 結構成員 struct card *face *suit 10.2 結構定義 • Example struct card { char *face; char *suit;}; • struct 定義結構 card • card為結構的名稱，可和struct一起用來宣告該結構型別的變數 • card包含兩個型別為 char * 的成員變數 • 成員變數為 face和 suit • 同一個結構中的成員名稱不可相同 • 不同結構中可以有相同名稱的成員 • 每個結構定義必須由分號結束 • 結構的成員可以是自己之外的任何型態

  4. struct employee firstname[20] lastname[20] age gender hourlySalary *rPtr 10.2 結構定義 • Examples: struct employee { char firstname[20]; char lastname[20]; int age; char gender; double hourlySalary; struct employee2 person; /*Error */ struct employee2 *rPtr; };

  5. aCard *face *suit Deck[52] *face *suit *face *suit *face *cardPtr *suit *face *suit 10.2 結構定義 • 自我參照的結構 self-referential structure • 結構中任一個成員的資料型態都不能為該結構本身。 • 成員中有指向結構本身的指標 • 一個結構定義並沒有佔用任何記憶體 • 建立一個新的資料型別，以供變數宣告使用 • 定義 • 結構變數的宣告方式與宣告其他變數類似: struct card aCard, deck[ 52 ], *cardPtr; • 也可以直接放在結構定義的右大括號之後: struct card { char *face; char *suit; } aCard, deck[ 52 ], *cardPtr;

  6. 10.2 結構定義 • 合法的運算 • 設定結構給型態相同的結構變數 • 取得結構變數的位址 (&) • 存取結構變數的成員 • 使用 sizeof運算子來計算結構變數的大小

  7. aCard “Three” *face *suit “Hearts” ThreeHearts *face “Three” *suit “Hearts” 10.3結構初始值設定 • 初始值串列 • Example: struct card aCard = { "Three", "Hearts" }; • 設定 • 定義並設定初始值 threeHearts : struct card threeHearts; threeHearts.face = “Three”; threeHearts.suit = “Hearts”;

  8. aCard “Three” *face *suit “Hearts” *cardPtr 10.4 存取結構成員 • 存取結構成員 • 結構成員運算子(點運算子)(.): 存取結構成員 struct card aCard; printf( "%s", aCard.suit ); • 結構指標運算子(箭號運算子)(->): 透過指向結構的指標來存取結構成員 struct card *CardPtr = &aCard; printf( "%s", CardPtr->suit ); • CardPtr->suit相同於 ( *CardPtr ).suit

  9. a “Ace” *face *aPtr *suit “Spades” struct card *face *suit

  10. a “Ace” *face *aPtr *suit “Spades” Ace of Spades Ace of Spades Ace of Spades

  11. 10.5 使用結構與函數 • 將結構傳給函數 • 傳遞整個結構 • 傳遞個別的結構成員 • 均為 call-by-value (傳值呼叫) • 利用 call-by-reference (傳參照呼叫)傳遞結構 • 傳遞位址(參照) • 利用 call-by-value傳遞陣列 • 產生一個包含陣列成員的結構 • 然後傳遞結構

  12. 10.6typedef • typedef • 為之前定義的資料型別定義別名 • 使用 typedef建立較短的型別名稱 • Example: typedef struct card Card; • 定義新的資料名稱 Card為 struct card 的別名 • typedef並不建立一個新的資料型別

  13. 10.7 Example:高效率的洗牌與發牌 • Pseudocode: • Create an array of card structures • Put cards in the deck • Shuffle the deck(洗牌) • Deal the cards(發牌)

  14. struct card *face *suit

  15. 0 1 deck[52] *face *suit *face 51 *suit *face *suit

  16. 0 0 1 1 deck[52] deck[52] *face *face Ace Four *suit *suit Hearts Clubs *face *face Deuce Threee 51 51 *suit *suit Hearts Heart *face *face King King *suit *suit Spades Diamonds wDeck const wDeck

  17. Four of Clubs Three of Hearts Three of Diamonds Three of Spades Four of Diamonds Ace of Diamonds Nine of Hearts Ten of Clubs Three of Clubs Four of Hearts Eight of Clubs Nine of Diamonds Deuce of Clubs Queen of Clubs Seven of Clubs Jack of Spades Ace of Clubs Five of Diamonds Ace of Spades Five of Clubs Seven of Diamonds Six of Spades Eight of Spades Queen of Hearts Five of Spades Deuce of Diamonds Queen of Spades Six of Hearts Queen of Diamonds Seven of Hearts Jack of Diamonds Nine of Spades Eight of Hearts Five of Hearts King of Spades Six of Clubs Eight of Diamonds Ten of Spades Ace of Hearts King of Hearts Four of Spades Jack of Hearts Deuce of Hearts Jack of Clubs Deuce of Spades Ten of Diamonds Seven of Spades Nine of Clubs King of Clubs Six of Diamonds Ten of Hearts King of Diamonds

  18. union Number value X (或y) X (或y) 10.8 Unions • union • 在不同時間下，含有多個資料型別 • 但在同一時間，只有一個成員可進行參照(被指定值) • union的成員共用相同的儲存體空間 • 可以節省儲存空間 • 定義union • 類似結構 union Number { int x; float y; }; union Number value;

  19. 10.8 Unions • 合法的union運算 • 設定給型態相同的union變數 : = • 取得union變數的位址 : & • 存取union變數的成員: . • 使用指標存取union變數的成員: ->

  20. union Number value value X (或y) X (或y) X 100

  21. Put a value in the integer member and print both members. int: 100 double: -92559592117433136000000000000000000000000000000000000000000000.000000 Put a value in the floating member and print both members. int: 0 double: 100.000000

  22. 10.9 位元運算子 • 所有資料在電腦的內部均是以一連串的位元(bit)來加以表示 • 每個位元的值可以是0或1 • 位元運算子都會將整數運算元以二進位制加以處理

  23. Enter an unsigned integer: 65000 65000 = 00000000 00000000 11111101 11101000

  24. 10.9 位元運算子

  25. The result of combining the following 65535 = 00000000 00000000 11111111 11111111 1 = 00000000 00000000 00000000 00000001 using the bitwise AND operator & is 1 = 00000000 00000000 00000000 00000001 The result of combining the following 15 = 00000000 00000000 00000000 00001111 241 = 00000000 00000000 00000000 11110001 using the bitwise inclusive OR operator | is 255 = 00000000 00000000 00000000 11111111 The result of combining the following 139 = 00000000 00000000 00000000 10001011 199 = 00000000 00000000 00000000 11000111 using the bitwise exclusive OR operator ^ is 76 = 00000000 00000000 00000000 01001100 The one's complement of 21845 = 00000000 00000000 01010101 01010101 is 4294945450 = 11111111 11111111 10101010 10101010

  26. 10.9 位元運算子

  27. 10.9 位元運算子

  28. The result of left shifting 960 = 00000000 00000000 00000011 11000000 8 bit positions using the left shift operator << is 245760 = 00000000 00000011 11000000 00000000 The result of right shifting 960 = 00000000 00000000 00000011 11000000 8 bit positions using the right shift operator >> is 3 = 00000000 00000000 00000000 00000011

  29. 10.9 位元運算子

  30. 10.9 位元運算子

  31. 10.10 位元欄位 • Bit field • Member of a structure whose size (in bits) has been specified • Enable better memory utilization • Must be defined as int or unsigned • Cannot access individual bits • Defining bit fields • Follow unsigned or int member with a colon (:) and an integer constant representing the width of the field • Example: struct BitCard { unsigned face : 4; unsigned suit : 2; unsigned color : 1; };

  32. 10.10 位元欄位 • Unnamed bit field • Field used as padding in the structure • Nothing may be stored in the bits struct Example { unsigned a : 13; unsigned : 3; unsigned b : 4; } • Unnamed bit field with zero width aligns next bit field to a new storage unit boundary

  33. Card: 0 Suit: 0 Color: 0 Card: 0 Suit: 2 Color: 1 Card: 1 Suit: 0 Color: 0 Card: 1 Suit: 2 Color: 1 Card: 2 Suit: 0 Color: 0 Card: 2 Suit: 2 Color: 1 Card: 3 Suit: 0 Color: 0 Card: 3 Suit: 2 Color: 1 Card: 4 Suit: 0 Color: 0 Card: 4 Suit: 2 Color: 1 Card: 5 Suit: 0 Color: 0 Card: 5 Suit: 2 Color: 1 Card: 6 Suit: 0 Color: 0 Card: 6 Suit: 2 Color: 1 Card: 7 Suit: 0 Color: 0 Card: 7 Suit: 2 Color: 1 Card: 8 Suit: 0 Color: 0 Card: 8 Suit: 2 Color: 1 Card: 9 Suit: 0 Color: 0 Card: 9 Suit: 2 Color: 1 Card: 10 Suit: 0 Color: 0 Card: 10 Suit: 2 Color: 1 Card: 11 Suit: 0 Color: 0 Card: 11 Suit: 2 Color: 1 Card: 12 Suit: 0 Color: 0 Card: 12 Suit: 2 Color: 1 Card: 0 Suit: 1 Color: 0 Card: 0 Suit: 3 Color: 1 Card: 1 Suit: 1 Color: 0 Card: 1 Suit: 3 Color: 1 Card: 2 Suit: 1 Color: 0 Card: 2 Suit: 3 Color: 1 Card: 3 Suit: 1 Color: 0 Card: 3 Suit: 3 Color: 1 Card: 4 Suit: 1 Color: 0 Card: 4 Suit: 3 Color: 1 Card: 5 Suit: 1 Color: 0 Card: 5 Suit: 3 Color: 1 Card: 6 Suit: 1 Color: 0 Card: 6 Suit: 3 Color: 1 Card: 7 Suit: 1 Color: 0 Card: 7 Suit: 3 Color: 1 Card: 8 Suit: 1 Color: 0 Card: 8 Suit: 3 Color: 1 Card: 9 Suit: 1 Color: 0 Card: 9 Suit: 3 Color: 1 Card: 10 Suit: 1 Color: 0 Card: 10 Suit: 3 Color: 1 Card: 11 Suit: 1 Color: 0 Card: 11 Suit: 3 Color: 1 Card: 12 Suit: 1 Color: 0 Card: 12 Suit: 3 Color: 1

  34. 10.11 列舉型別常數 • 列舉型別 • 一組由識別字所代表的整數常數 • 列舉型別常數事實上便是一些會自動設定數值的符號常數 • 數值從0開始，然後逐漸遞增1 • 數值也可使使用等號(=)來設定 • 列舉型別內的常數識別字必須是唯一的 • Example1: enum months { JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC}; • 產生一個新的型別 enum months ，其內的識別字分別會設定為0到 11的整數

  35. 10.11 列舉型別常數 • Example 2: enum months { JAN = 1, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC}; • 產生一個新的型別 enum months ，其內的識別字分別會設定為1到 12的整數

  36. 1 January 2 February 3 March 4 April 5 May 6 June 7 July 8 August 9 September 10 October 11 November 12 December

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