STL map.find 返回所有元素

Question

Having a problem with undefined behaviour of STL map defined as follows:

typedef bool (*SNAPSHOT_CALLBACK)(/*Some params here..*/);
typedef std::map<DWORD, SNAPSHOT_CALLBACK> SnapshotsMap;
SnapshotsMap m_mapCallbacks;

insertion:

AddCallback(DWORD snapshotType, SNAPSHOT_CALLBACK callback)
    m_mapCallbacks.insert(std::pair<DWORD, SNAPSHOT_CALLBACK>(snapshotType, callback));

and query:

for (auto itr = m_mapCallbacks.find(cpyHeader->hdr); itr != m_mapCallbacks.end(); itr++)
{
   itr->second();
}

The problem that I'm having is on a single key search the iterator retrieves both keys that I have inserted. My logs:

Insert:
   Added callback type: 21000b Callback: 615F5AE0
   Added callback type: 210136 Callback: 615F5480
Query:
   Same iterator loop:
      Key to find: 21000b -> FOUND First: 21000b Second: 61da5ae0
      Key to find: 21000b -> FOUND First: 210136 Second: 61da5480

for some reason both elements get retrieved and there's no other modifications/thread on this map. Some help would be much appreciated:)

Answer 1

Query should be

// C++17 if construct
if (auto itr = m_mapCallbacks.find(cpyHeader->hdr); itr != m_mapCallbacks.end())
{
   itr->second();
}

or

// pre-C++17 (but C++11 for auto)
auto itr = m_mapCallbacks.find(cpyHeader->hdr);
if (itr != m_mapCallbacks.end())
{
   itr->second();
}

Your for iterates from found key until the end (so only (potentially) skips first elements)