C：哈希表 - 为什么不编译？

我有以下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 std::tr1::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 int, const char*, hash<const int>, eqstr> months;

  months.set_empty_key(0);
  months[1234] = "1234";

  cout << "1234:" << months[1234] << endl;
}

如您所见，我正在使用Google的sparsehash库实现哈希表 .

我使用整数作为键和字符串作为值 .

但我不断得到以下编译错误，我无法深究：

make all Building文件：../ src / Main.cpp调用：GCC C编译器g -O0 -g3 -Wall -c -fmessage-length = 0 -MMD -MP -MF“src / Main.d”-MT“ src / Main.d“ - o”src / Main.o“”../src/Main.cpp“在/ usr / local / include / google / dense_hash_map中包含的文件：104：0，来自../src/ Main.cpp：2：/usr/local/include/google/sparsehash/densehashtable.h：在成员函数'bool google :: dense_hashtable :: KeyInfo :: equals（const key_type＆，const key_type＆）const [with Value = std： ：pair，Key = int，HashFcn = std :: tr1 :: hash，ExtractKey = google :: dense_hash_map，eqstr> :: SelectKey，SetKey = google :: dense_hash_map，eqstr> :: SetKey，EqualKey = eqstr，Alloc = google :: libc_allocator_with_realloc，key_type = int]'：/usr/local/include/google/sparsehash/densehashtable.h：1306：32：从'bool google :: dense_hashtable :: equals（const key_type＆，const key_type＆）const [实例化] Value = std :: pair，Key = int，HashFcn = std :: tr1 :: hash，ExtractKey = google :: dense_hash_map，eqstr> :: SelectKey，SetKey = google :: dense_hash_ma p，eqstr> :: SetKey，EqualKey = eqstr，Alloc = google :: libc_allocator_with_realloc，key_type = int]'/usr/local/include/google/sparsehash/densehashtable.h:514：5：从'void google ::实例化dense_hashtable :: set_empty_key（google :: dense_hashtable :: const_reference）[with Value = std :: pair，Key = int，HashFcn = std :: tr1 :: hash，ExtractKey = google :: dense_hash_map，eqstr> :: SelectKey，SetKey = google :: dense_hash_map，eqstr> :: SetKey，EqualKey = eqstr，Alloc = google :: libc_allocator_with_realloc，google :: dense_hashtable :: const_reference = const std :: pair＆]'/ usr / local / include / google / dense_hash_map：298 ：5：从'void google :: dense_hash_map :: set_empty_key（google :: dense_hash_map :: key_type＆）实例化[使用Key = int，T = const char *，HashFcn = std :: tr1 :: hash，EqualKey = eqstr，Alloc = google :: libc_allocator_with_realloc，google :: dense_hash_map :: key_type = int]'../src/Main.cpp:21:25：从这里实例化/usr/local/include/google/sparsehash/densehashtable.h:1293： 39：错误：inval id转换来自'google :: dense_hashtable，int，std :: tr1 :: hash，google :: dense_hash_map，eqstr，google :: libc_allocator_with_realloc :: SelectKey，eqstr，google :: libc_allocator_with_realloc，google :: dense_hash_map，eqstr，google： ：libc_allocator_with_realloc >> :: SetKey，eqstr，google :: libc_allocator_with_realloc，eqstr，google :: libc_allocator_with_realloc >>> :: key_type'到'const char *'/usr/local/include/google/sparsehash/densehashtable.h:1293： 39：错误：初始化'bool eqstr :: operator（）的参数1（const char *，const char *）const'/usr/local/include/google/sparsehash/densehashtable.h:1293:39：错误：转换无效来自'google :: dense_hashtable，int，std :: tr1 :: hash，google :: dense_hash_map，eqstr，google :: libc_allocator_with_realloc :: SelectKey，eqstr，google :: libc_allocator_with_realloc，google :: dense_hash_map，eqstr，google :: libc_allocator_with_realloc >>> :: SetKey，eqstr，google :: libc_allocator_with_realloc，eqstr，google :: libc_allocator_with_realloc >> :: ke y_type'到'const char *'/usr/local/include/google/sparsehash/densehashtable.h:1293:39：错误：初始化'bool eqstr :: operator（）的参数2（const char *，const char ） const'make： [src / Main.o]错误1

它似乎非常冗长，我无法理解它 .

我应该补充说，当我使用字符串作为键和整数作为值时，它可以正常工作：

dense_hash_map<const char*, int, hash<const char*>, eqstr> months;
...
months["february"] = 2;   //works fine

有人有任何想法吗？

提前谢谢了，

编辑：现在就搞定了！

#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 std::tr1::hash;  // or __gnu_cxx::hash, or maybe tr1::hash, depending on your OS

struct eqstr
{
  bool operator()(int s1, int s2) const
  {
    return (s1 == s2); //|| (s1 && s2 && strcmp(s1, s2) == 0);
  }
};

int main(void){
  dense_hash_map<int, const char*, hash<int>, eqstr> months;

  months.set_empty_key(0);
  months[1234] = "1234";

  cout << "1234:" << months[1234] << endl;
}

完全忘了编辑eqstr结构来容纳新的数据类型...刘海离开 table