vector是連續(xù)存儲(chǔ)結(jié)構(gòu)，支持隨機(jī)的高效的隨機(jī)和在尾部進(jìn)行插入、刪除操作，其它位置的插入、刪除操作相對(duì)來(lái)說(shuō)效率較低。
vector相當(dāng)于一個(gè)數(shù)組，但它的數(shù)組空間大小需要寫一程序來(lái)實(shí)現(xiàn)。
它的內(nèi)存分配原理大概可分為下面幾步：
1）首先分配一塊內(nèi)存空間進(jìn)行存儲(chǔ)；
2）當(dāng)所需存儲(chǔ)的數(shù)據(jù)超過(guò)分配的空間時(shí)，再重新分配一塊空間；
3）將舊元素復(fù)制到新空間；
4）釋放舊空間。
實(shí)現(xiàn)代碼如下：
vector.h
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
#pragma once#include<stdio.h>#include<assert.h>#include<string.h>#include<iostream>using namespace std;typedef int DataType;class Vector{public: Vector() :_first(NULL), _finish(NULL), _endofstorage(NULL) {} Vector(const Vector& v){ if (v.Size() > 0){ _first = new DataType(v.Size()); memcpy(_first, v._first, sizeof (DataType)*v.Size()); } if (_first > 0){ _finish = _first + v.Size(); _endofstorage = _first + v.Size(); } _first = _finish = _endofstorage = NULL; } Vector& operator=(const Vector& v){ if (this != &v){ /*swap(_first, v._first); swap(_finish, v._finish); swap(_endofstorage, v._endofstorage);*/ DataType* tmp = new DataType(v.Size()); memcpy(tmp, _first, sizeof(DataType)*v.Size()); delete _first; _first = tmp; _finish = _first + v.Size(); _endofstorage = _first + v.Size(); } return *this; } ~Vector(){ delete[] _first; _first = _finish = _endofstorage = NULL; } void Print(){ DataType* cur = _first; while (cur != _first){ cout << "*cur" << endl; cur++; } cout << endl; } size_t Size() const{ return _finish - _first; } size_t Capacity() const{ return _endofstorage - _first; } void Expand(size_t n){ if (n > Capacity()){ DataType* tmp = new DataType(n); size_t size = Size(); memcpy(tmp, _first, sizeof(DataType)*size); delete[] _first; _first = tmp; _finish = _first + size; _endofstorage = _first + n; } } void PushBack(DataType x){ if (_finish == _endofstorage){ size_t capacity = Capacity() > 0 ? Capacity() * 2 : 3; Expand(capacity); /*if (Capacity() == 0){ Expand(3); } else{ Expand(Capacity() * 2); }*/ } *_finish = x; ++_finish; } void PopBack(){ assert(_finish > _first); --_finish; } void Reserve(size_t n){ if (n > Capacity()){ Expand(n); } } void Insert(size_t pos, DataType x){ assert(pos < Size()); if (_finish = _endofstorage){ size_t capacity = Capacity() > 0 ? Capacity() * 2 : 3; Expand(capacity); } int tmp = Size() - 1; while (tmp >= (int)pos){ _first[tmp + 1] = _first[tmp]; --tmp; } _first[pos] = x; ++_finish; } void Erase(size_t pos){ assert(pos < Size()); size_t cur = pos; while (cur < Size()-1){ _first[cur] = _first[cur] + 1; ++cur; } --_finish; } size_t Find(DataType x){ DataType *cur = _first; while (cur != _finish){ if (*cur == x){ return cur - _first; } ++cur; } return -1; }private: DataType* _first; DataType* _finish; DataType* _endofstorage;}; |
test.cpp
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
#include"vector.h"void Tset(){ Vector v; v.PushBack(1); v.PushBack(2); v.PushBack(3); v.PushBack(4); v.PopBack(); v.Print(); size_t pos = v.Find(1); printf("pos->data:expcet 1,axtual %lu", pos); Vector v1; v1.Insert(1, 0); v1.Print(); Vector v2; v2.Erase(3); v2.Print();}int main(){ Tset(); return 0;} |
以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持服務(wù)器之家。
原文鏈接：https://blog.csdn.net/getitstarted/article/details/80329067
