STL hash problem

[Ana_Developer]

Hello all,

I am having a hash_map with key: char *. I have defined it like this:

struct eqstr
{
  bool operator()(const char* s1, const char* s2) const
  {
    return strcmp(s1, s2) == 0;
  }
};

...
hash_map<char *,map<uint16_t,set<float>>, hash<const char *>,eqstr> symbol_hm;

but I get an error (error C2065: 'hash' : undeclared identifier) for the hash<const char *> part. How can I fix this? Which header should I include?

Thanks!

[griswolf]

well, I see that your code is identical to what I found at the sgi site. A little more exploration yields this:

Defined in the headers hash_map and hash_set, and in the backward-compatibility headers hash_map.h and hash_set.h. This class is an SGI extension; it is not part of the C++ standard.

So you will have to either write your own, get the sgi STL, or otherwise work around that issue (boost?).

[m4ster_r0shi]

map<uint16_t,set<float[U]>>[/U] <- This here means the OP uses Visual Studio ;)

This should work -> http://msdn.microsoft.com/en-us/library/0d462wfh(v=VS.90).aspx

[mike_2000_17]

hash_map is deprecated. You should use unordered_map instead. It is a C++0x standard feature, but most compiler vendors support it already, without having to compile with the C++0x experimental support flag. Other than that, I am not familiar with std::hash, so I don't know how to solve your problem. But std::hash should be in the <utility> header.