我从谷歌的sparsehash网站获得了以下C代码:
#include <iostream>
#include <google/dense_hash_map>
#include <string.h>
using google::dense_hash_map; // namespace where class lives by default
using std::cout;
using std::endl;
using ext::hash; // or __gnu_cxx::hash, or maybe tr1::hash, depending on your OS
struct eqstr
{
bool operator()(const char* s1, const char* s2) const
{
return (s1 == s2) || (s1 && s2 && strcmp(s1, s2) == 0);
}
};
int main(void){
dense_hash_map<const char*, int, hash<const char*>, eqstr> months;
months.set_empty_key(NULL);
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;
}
我收到以下错误:
使用ext :: hash
‘ext’ has not been declared
dense_hash_map< const char *,int,hash< const char *> ;,eqstr>个月;
- ‘hash’ was not declared in this scope
- template argument 3 is invalid
- expected unqualified-id before ‘,’ token
- expected initializer before ‘>’ token
和months.set_empty_key(NULL);
‘months’ was not declared in this scope
我有点像C菜鸟,希望有人能指出我正确的方向.
提前谢谢了,
解决方法:
也许你应该尝试用tr1 :: hash替换ext :: hash.