Data Abstraction(Chapter 4 of Thinking in C++)
时间：2010-11-10 来源：Ray Z
CppLib.cpp
1 #include "CppLib.h"2 #include <iostream>
3 #include <cassert>
4 using namespace std;
5
6 const int increment = 100;
7
8 void Stash::initialize(int size)
9 {
10 this->size = size;
11 quantity = 0;
12 storage = 0;
13 next = 0;
14 }
15
16 int Stash::add(const void* element)
17 {
18 if(next >= quantity)
19 {
20 inflate(increment);
21 }
22
23 int startBytes = next * size;
24 unsigned char* e = (unsigned char*)element;
25 for(int i=0; i<size; i++)
26 {
27 storage[startBytes+i] = e[i];
28 }
29 next++;
30 return (next-1);
31 }
32
33 void* Stash::fetch(int index)
34 {
35 assert(0 <= index);
36 if(index >= next)
37 {
38 return 0;
39 }
40
41 return &(storage[index * size]);
42 }
43
44 int Stash::count()
45 {
46 return next;
47 }
48
49 void Stash::inflate(int increase)
50 {
51 assert(increase > 0);
52 int newQuantity = quantity + increase;
53 int newBytes = newQuantity * size;
54 int oldBytes = quantity * size;
55 unsigned char* b = new unsigned char[newBytes];
56 for(int i=0; i<oldBytes; i++)
57 {
58 b[i] = storage[i];
59 }
60 delete []storage;
61 storage = b;
62 quantity = newQuantity;
63 }
64
65 void Stash::cleanup()
66 {
67 if(storage != 0)
68 {
69 cout << "freeeing storage" << endl;
70 delete []storage;
71 }
72 }
CppLibTest.cpp
1 #include "CppLib.h"2 #include <fstream>
3 #include <iostream>
4 #include <string>
5 using namespace std;
6
7 int main()
8 {
9 Stash intStash;
10 intStash.initialize(sizeof(int));
11 for(int i=0; i<100; i++)
12 {
13 intStash.add(&i);
14 }
15
16 for(int j=0; j<intStash.count(); j++)
17 {
18 cout << "intStash.fetch(" << j << ") = "
19 << *(int*)intStash.fetch(j) << endl;
20 }
21
22 Stash stringStash;
23 const int bufsize = 80;
24 stringStash.initialize(sizeof(char) * bufsize);
25 ifstream in("CppLibTest.cpp");
26 string line;
27 while(getline(in, line))
28 {
29 stringStash.add(line.c_str());
30 }
31
32 int k=0;
33 char* cp;
34 while((cp = (char*)stringStash.fetch(k++)) != 0)
35 {
36 cout << "stringStash.fetch(" << k << ") = "
37 << cp << endl;
38 }
39
40 intStash.cleanup();
41 stringStash.cleanup();
42 cin.get();
43 }
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