几种C++多维数组管理方法的性能测试

为了测试几种常用的原生多维数组管理方法，我们利用GNU C++ 7.2 最新的MSYS2版本，进行一个测试: 
主要测试涵盖指针型的二维数组、vector\array\map

#include <vector>#include <array>#include <functional>#include <map>#include <unordered_map>#include <stdio.h>#include <time.h>#include <malloc.h>#include <memory>#include <typeinfo>//GNU C++ 7.2//链接选项: -Wl,--stack,20240000using namespace std;const int testloopTimes = 1000;const int d1 = 80;const int d2 = 60;const int d3 = 40;const int d4 = 20;//用于进行循环赋值测试的函数template <typename T>double function_loop(T p, int Ntimes){    double  duration = 0;    clock_t start, finish;    start=clock();    for (int c=0;c<Ntimes;++c)        for(int h=0; h<d1; h++)            for(int i=0; i<d2; i++)                for(int j=0; j<d3; j++)                    for(int k=0; k<d4; k++)                        p[h][i][j][k]=h*60+i*20+j*5+k + c;    finish=clock();    duration=(double)(finish-start)/CLOCKS_PER_SEC;    if (Ntimes>1)        printf("\tloop cost: %f (s)\n",duration);    return duration;}//用于测试含有构造、析构的函数void test(function<double (void)> ftest){    double  duration = 0;    clock_t start, finish;    start=clock();    double loopCost = ftest();    finish=clock();    duration=(double)(finish-start)/CLOCKS_PER_SEC;    printf("\tMEM  cost: %f (s)\n",duration - loopCost );}//vector 测试double function_vector(){    vector<vector<vector<vector<int> > > >            p(d1,vector<vector<vector<int> > >              (d2,vector<vector<int> >               (d3,vector<int>(d4,0))));    printf ("test vector:\n");    double loopCost = function_loop(p,testloopTimes);    return loopCost;}//array 测试double function_array(){    array<array<array<array<int,d4 >,d3 >,d2 >,d1> p{0};    printf ("test array:\n");    double loopCost = function_loop(p,testloopTimes);    return loopCost;}//map 测试double function_map(){    map<int,map<int,map<int,map<int,int > > >> p;    printf ("test map:\n");    function_loop(p,1);    double loopCost = function_loop(p,testloopTimes);    return loopCost;}//unordered_map 测试double function_unordered_map(){    unordered_map<int,unordered_map<int,unordered_map            <int,unordered_map<int,int > > >> p;    printf ("test unordered_map:\n");    function_loop(p,1);    double loopCost = function_loop(p,testloopTimes);    return loopCost;}//shared_ptr 测试#if __GNUC__>= 7double function_shared_ptr(){    shared_ptr<int[][d2][d3][d4]> p (new int [d1][d2][d3][d4]);    printf ("test shared_ptr:\n");    double loopCost = function_loop(p,testloopTimes);    return loopCost;}#endif//pointer测试double function_pointer(){    printf ("test pointer:\n");    int ****p = nullptr;    int h,i,j;    p=new int ***[d1];    if (nullptr==p) return 0;    for (h=0; h<d1; h++)    {        p[h]=new int ** [d2];        if (nullptr==p[h]) return 0;        for (i=0; i<d2; i++)        {            p[h][i]=new int *[d3];            if (nullptr==p[h][i]) return 0;            for (j=0; j<d3; j++)            {                p[h][i][j]=new int [d4];                if (nullptr==p[h][i][j]) return 0;            }        }    }    double loopCost = function_loop(p,testloopTimes);    for (h=0; h<d1; h++)    {        for (i=0; i<d2; i++)        {            for (j=0; j<d3; j++)            {                delete [] p[h][i][j];            }            delete [] p[h][i];        }        delete [] p[h];    }    delete [] p;    return loopCost;}int main(){    test(function_vector);    test(function_array);    test(function_pointer);    test(function_map);    test(function_unordered_map);#if __GNUC__>= 7    test(function_shared_ptr);#endif    return 0;}
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
148
149
150
151
152

输出结果如下：

test vector:        loop cost: 1.594000 (s)        MEM  cost: 0.046000 (s)test array:        loop cost: 1.204000 (s)        MEM  cost: 0.000000 (s)test pointer:        loop cost: 1.500000 (s)        MEM  cost: 0.015000 (s)test map:        loop cost: 156.454000 (s)        MEM  cost: 0.563000 (s)test unordered_map:        loop cost: 83.639000 (s)        MEM  cost: 0.609000 (s)test shared_ptr:        loop cost: 1.219000 (s)        MEM  cost: 0.015000 (s)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

可见，使用 shared_ptr 还是很划算的！用array、vector也不赖！