'hash_map' was not declared in this scope with g++ 4.2.1
c++, sgi
Solution
The include file `<ext/hash_map>` refers to the GNU extension hash map class and this is declared in namespace `__gnu_cxx`. You can either explicitly qualify the template name or add:
using namespace __gnu_cxx;
Problem
I am trying to use sgi hash_map. ``` #include <list> #include <iostream> #include <string> #include <map> #include <cstring> #include <tr1/unordered_map> #include <ext/hash_map> using namespace std; struct eqstr { bool operator()(const char* s1, const char* s2) const { return strcmp(s1, s2) == 0; } }; int main() { hash_map<const char*, int, hash<const char*>, eqstr> months; months["january"] = 31; months["february"] = 28; months["march"] = 31; months["april"] = 30; months["may"] = 31; months["june"] = 30; months["july"] = 31; months["august"] = 31; months["september"] = 30; months["october"] = 31; months["november"] = 30; months["december"] = 31; cout << "september -> " << months["september"] << endl; cout << "april -> " << months["april"] << endl; cout << "june -> " << months["june"] << endl; cout << "november -> " << months["november"] << endl; } ``` on gcc4.2 I am getting the error ``` listcheck.cc: In function 'int main()': listcheck.cc:22: error: 'hash_map' was not declared in this scope listcheck.cc:22: error: expected primary-expression before 'const' listcheck.cc:22: error: expected `;' before 'const' listcheck.cc:24: error: 'months' was not declared in this scope ``` while the same code compile with 3.4.