在std :: map中使用char *作为键 [英] Using char* as a key in std::map

问题描述

我想弄清楚为什么下面的代码不工作，我假设这是一个问题，使用char *作为键类型，但我不知道如何可以解决它或为什么它发生。我使用的所有其他函数（在HL2 SDK中）使用 char * ，因此使用 std :: string 导致很多不必要的并发症。

I am trying to figure out why the following code is not working, and I am assuming it is an issue with using char* as the key type, however I am not sure how I can resolve it or why it is occuring. All of the other functions I use (in the HL2 SDK) use char* so using std::string is going to cause a lot of unnecessary complications.

std::map<char*, int> g_PlayerNames;

int PlayerManager::CreateFakePlayer()
{
    FakePlayer *player = new FakePlayer();
    int index = g_FakePlayers.AddToTail(player);

    bool foundName = false;

    // Iterate through Player Names and find an Unused one
    for(std::map<char*,int>::iterator it = g_PlayerNames.begin(); it != g_PlayerNames.end(); ++it)
    {
        if(it->second == NAME_AVAILABLE)
        {
            // We found an Available Name. Mark as Unavailable and move it to the end of the list
            foundName = true;
            g_FakePlayers.Element(index)->name = it->first;

            g_PlayerNames.insert(std::pair<char*, int>(it->first, NAME_UNAVAILABLE));
            g_PlayerNames.erase(it); // Remove name since we added it to the end of the list

            break;
        }
    }

    // If we can't find a usable name, just user 'player'
    if(!foundName)
    {
        g_FakePlayers.Element(index)->name = "player";
    }

    g_FakePlayers.Element(index)->connectTime = time(NULL);
    g_FakePlayers.Element(index)->score = 0;

    return index;
}

推荐答案

函数到地图，否则比较char *指针而不是字符串。一般来说，这是任何时候你想要你的地图键是一个指针的情况。

You need to give a comparison functor to the map otherwise it's comparing the char* pointer not the string. In general, this is the case anytime you want your map key to be a pointer.

即

struct cmp_str
{
   bool operator()(char const *a, char const *b)
   {
      return std::strcmp(a, b) < 0;
   }
};

map<char *, int, cmp_str> BlahBlah;

编辑：完全忽略我的编辑，函数更容易使用。

Acutally disregard my edit, the functor is easier to use.

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