c++ - What is the "right" way to use a GUID as the key in std::hash_map -

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i want say

std::hash_map<guid, int> foo;

i believe must create 

bool operator < (const guid &guid1, const guid &guid2); std::size_t hash_value(guid const &b);

what proper way compare guids? (memcmp?) - proper way generate hash?

it'd great if flesh out these 2 functions, i've read dozens of posts give final clue :-)

from documentation seems that:

typedef struct _guid {   dword data1;   word  data2;   word  data3;   byte  data4[8]; } guid;

there several possibilities

building own

for comparison i'd go item item

bool operator < (const guid &guid1, const guid &guid2) {     if(guid1.data1!=guid2.data1) {         return guid1.data1 < guid2.data1;     }     if(guid1.data2!=guid2.data2) {         return guid1.data2 < guid2.data2;     }     if(guid1.data3!=guid2.data3) {         return guid1.data3 < guid2.data3;     }     for(int i=0;i<8;i++) {         if(guid1.data4[i]!=guid2.data4[i]) {             return guid1.data4[i] < guid2.data4[i];         }     }     return false; }

for hashing... i'd go uuidhash function (note guid form of uuid indicated in uuid definition)

going strings

use stringfromclsid string guids... once have string, have operators.

... more expensive.


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