链表ADT的实现
list.h文件
1 /*链表的类型声明*/ 2 3 typedef int ElementType; 4 5 /* START: fig3_6.txt */ 6 #ifndef _List_H 7 #define _List_H 8 9 struct Node; 10 typedef struct Node *PtrToNode; 11 typedef PtrToNode List; 12 typedef PtrToNode Position; 13 14 List MakeEmpty( List L ); 15 int IsEmpty( List L ); 16 int IsLast( Position P, List L ); 17 Position Find( ElementType X, List L ); 18 void Delete( ElementType X, List L ); 19 Position FindPrevious( ElementType X, List L ); 20 void Insert( ElementType X, List L, Position P ); 21 void DeleteList( List L ); 22 Position Header( List L ); 23 Position First( List L ); 24 Position Advance( Position P ); 25 ElementType Retrieve( Position P ); 26 27 #endif /* _List_H */ 28 /* END */
list.c文件
1 #include "list.h" 2 #include <stdlib.h> 3 #include "fatal.h" 4 5 /* Place in the interface file */ 6 struct Node 7 { 8 ElementType Element; 9 Position Next; 10 }; 11 12 /*创建空链表*/ 13 List 14 MakeEmpty( List L ) 15 { 16 if( L != NULL ) 17 DeleteList( L ); 18 L = malloc( sizeof( struct Node ) ); 19 if( L == NULL ) 20 FatalError( "Out of memory!" ); 21 L->Next = NULL; 22 return L; 23 } 24 25 /* START: fig3_8.txt */ 26 /* Return true if L is empty */ 27 28 /*判断链表是否为空*/ 29 int 30 IsEmpty( List L ) 31 { 32 return L->Next == NULL; 33 } 34 /* END */ 35 36 /* START: fig3_9.txt */ 37 /* Return true if P is the last position in list L */ 38 /* Parameter L is unused in this implementation */ 39 40 /*判断是否为链表的最后元素*/ 41 int IsLast( Position P, List L ) 42 { 43 return P->Next == NULL; 44 } 45 /* END */ 46 47 /* START: fig3_10.txt */ 48 /* Return Position of X in L; NULL if not found */ 49 50 /*找某元素的位置*/ 51 Position 52 Find( ElementType X, List L ) 53 { 54 Position P; 55 56 /* 1*/ P = L->Next; 57 /* 2*/ while( P != NULL && P->Element != X ) 58 /* 3*/ P = P->Next; 59 60 /* 4*/ return P; 61 } 62 /* END */ 63 64 /* START: fig3_11.txt */ 65 /* Delete from a list */ 66 /* Cell pointed to by P->Next is wiped out */ 67 /* Assume that the position is legal */ 68 /* Assume use of a header node */ 69 70 /*删除链表某个元素*/ 71 void 72 Delete( ElementType X, List L ) 73 { 74 Position P, TmpCell; 75 76 P = FindPrevious( X, L ); 77 78 if( !IsLast( P, L ) ) /* Assumption of header use */ 79 { /* X is found; delete it */ 80 TmpCell = P->Next; 81 P->Next = TmpCell->Next; /* Bypass deleted cell */ 82 free( TmpCell ); 83 } 84 } 85 /* END */ 86 87 /* START: fig3_12.txt */ 88 /* If X is not found, then Next field of returned value is NULL */ 89 /* Assumes a header */ 90 91 /*找某个元素的前一个元素*/ 92 Position 93 FindPrevious( ElementType X, List L ) 94 { 95 Position P; 96 97 /* 1*/ P = L; 98 /* 2*/ while( P->Next != NULL && P->Next->Element != X ) 99 /* 3*/ P = P->Next; 100 101 /* 4*/ return P; 102 } 103 /* END */ 104 105 /* START: fig3_13.txt */ 106 /* Insert (after legal position P) */ 107 /* Header implementation assumed */ 108 /* Parameter L is unused in this implementation */ 109 110 /*在某个位置后面插入一个元素*/ 111 void 112 Insert( ElementType X, List L, Position P ) 113 { 114 Position TmpCell; 115 116 /* 1*/ TmpCell = malloc( sizeof( struct Node ) ); 117 /* 2*/ if( TmpCell == NULL ) 118 /* 3*/ FatalError( "Out of space!!!" ); 119 120 /* 4*/ TmpCell->Element = X; 121 /* 5*/ TmpCell->Next = P->Next; 122 /* 6*/ P->Next = TmpCell; 123 } 124 /* END */ 125 126 #if 0 127 /* START: fig3_14.txt */ 128 /* Incorrect DeleteList algorithm */ 129 130 void 131 DeleteList( List L ) 132 { 133 Position P; 134 135 /* 1*/ P = L->Next; /* Header assumed */ 136 /* 2*/ L->Next = NULL; 137 /* 3*/ while( P != NULL ) 138 { 139 /* 4*/ free( P ); 140 /* 5*/ P = P->Next; 141 } 142 } 143 /* END */ 144 #endif 145 146 /* START: fig3_15.txt */ 147 /* Correct DeleteList algorithm */ 148 149 /*删除链表*/ 150 void 151 DeleteList( List L ) 152 { 153 Position P, Tmp; 154 155 /* 1*/ P = L->Next; /* Header assumed */ 156 /* 2*/ L->Next = NULL; 157 /* 3*/ while( P != NULL ) 158 { 159 /* 4*/ Tmp = P->Next; 160 /* 5*/ free( P ); 161 /* 6*/ P = Tmp; 162 } 163 } 164 /* END */ 165 166 /*返回头结点*/ 167 Position 168 Header( List L ) 169 { 170 return L; 171 } 172 173 /*返回第一个节点*/ 174 Position 175 First( List L ) 176 { 177 return L->Next; 178 } 179 /*返回某节点的下一个节点*/ 180 Position 181 Advance( Position P ) 182 { 183 return P->Next; 184 } 185 186 /*返回某节点的值*/ 187 ElementType 188 Retrieve( Position P ) 189 { 190 return P->Element; 191 }
