Re: hash_set was not declared even I #include<hash_set>

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 12 July 2011 07:42, eric wrote:
> Dear advanced c/g++ programers:
> ?I tried the following code
> -----------------------------------------------------------------------------------------
> // Example 6-8 Storing strings in a hast_set
> #include <iostream>
> #include <string>
> #include <hash_set>
> using namespace std;
>
> int main() {
>
> ?hash_set<std::string> hsString;
> ?string s = "bravo";
>
> ?hsString.insert(s);
> ?s = "alpha";
> ?hsString.insert(s);
> ?s = "charlie";
> ?hsString.insert(s);
>
> ?for (hash_set<string>::const_iterator p = hsString.begin();
> ? ? ? p != hsString.end(); ++p)
> ? ? cout << *p << endl; ? ?// Note that these aren't guaranteed
> ? ? ? ? ? ? ? ? ? ? ? ? ? ?// to be in sorted order
> }
> ---------------------------------------------------------------------------------------------------
> but I got the following compile error(g++ 4.5.2)
> ----------------------------------------------------------------
> eric@eric-laptop:~/cppcookbook/ch6$ g++ -Wno-deprecated Example6-8.cpp
> Example6-8.cpp: In function ‘int main()’:
> Example6-8.cpp:9:3: error: ‘hash_set’ was not declared in this scope

hash_set is non-standard, so it's not in namespace std.

http://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-api-4.5/a00055.html

Why don't you ask the authors of the book for corrections to the code,
or use a different book which has actually been tested with G++ and
contains working code?