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开发者_运维技巧 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.
Use <unordered_map>
. hash_map was a vendor specific extension, replaced by unordered_map.
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;
using namespace __gnu_cxx; removed the compilation error.
using
#include <hash_map>
gives this warning and removing gives a compilation error
In file included from /usr/include/c++/4.4/backward/hash_map:59,
from listcheck.cc:6:
/usr/include/c++/4.4/backward/backward_warning.h:28:2: warning: #warning This file includes at least one deprecated or antiquated header which may be removed without further notice at a future date. Please use a non-deprecated interface with equivalent functionality instead. For a listing of replacement headers and interfaces, consult the file backward_warning.h. To disable this warning use -Wno-deprecated.
after removing
#include <hash_map>
g++ listcheck.cc
listcheck.cc: In function ‘int main()’:
listcheck.cc:20: error: ‘hash_map’ was not declared in this scope
listcheck.cc:20: error: expected primary-expression before ‘const’
listcheck.cc:20: error: expected ‘;’ before ‘const’
listcheck.cc:21: error: ‘months’ was not declared in this scope
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