说起性能，没有测试，还是没有发言权：

#include

#include

#include

#include

#include

#include

#include

#include

#include

timeval g_ts;

long getnow(){

gettimeofday(&g_ts, NULL);

return g_ts.tv_usec;

}

int size = 10;

int getrand(){

return rand()%size;

}

int main(int agr, char** argc){

if (agr < 2){

printf("uage gar < 2\n");

exit(1);

}

size = atoi(argc[1]);

std::unordered_map map1;

long t1 = getnow();

for (int i = 0; i < size; ++i){

map1.insert(std::make_pair(getrand(),"tes"));

}

for(int i = 0; i < size; ++i){

map1.find(getrand());

}

int rand1 = getrand();

for (int i = 0; i < size; ++i){

map1.erase(getrand());

}

printf("unordered_map %d insert time:%ld\n", size, getnow()-t1);

std::map map2;

t1 = getnow();

for(int i = 0; i < size; ++i){

map2.insert(std::make_pair(getrand(), "tes"));

}

for(int i = 0; i < size; ++i){

map2.find(getrand());

}

for(int i = 0; i < size; ++i){

map2.erase(getrand());

}

printf("std::map insert&find %d times use:%ld\n", size, getnow() - t1);

}

输出结果为：

allen@allenPC:~/code/c++code$ ./tetsb 10

unordered_map 10 insert time:44

std::map insert&find 10 times use:33

allen@allenPC:~/code/c++code$ ./tetsb 100

unordered_map 100 insert time:186

std::map insert&find 100 times use:212

allen@allenPC:~/code/c++code$ ./tetsb 200

unordered_map 200 insert time:330

std::map insert&find 200 times use:453

allen@allenPC:~/code/c++code$ ./tetsb 500

unordered_map 500 insert time:792

std::map insert&find 500 times use:1236

allen@allenPC:~/code/c++code$ ./tetsb 1000

unordered_map 1000 insert time:1552

std::map insert&find 1000 times use:2587

allen@allenPC:~/code/c++code$

看来还是如果数据量较小，ｕｎｏｒｄｅｒｅｄｍａｐ更快！