更改为 std::vector 导致分段错误
changing to std::vector causing segmentation fault
你好，我有一个使用 new 关键字分配内存的结构，我想通过使用 std::vector 来删除，所以我这样做了
在更改为std::vector
之前
BYTE* packPlayerMoving(PlayerMoving* dataStruct)
{
BYTE* data = new BYTE[56];
for (int i = 0; i < 56; i++)
{
data[i] = 0;
}
memcpy(data, &dataStruct->packetType, 4);
memcpy(data + 4, &dataStruct->netID, 4);
memcpy(data + 12, &dataStruct->characterState, 4);
memcpy(data + 20, &dataStruct->plantingTree, 4);
memcpy(data + 24, &dataStruct->x, 4);
memcpy(data + 28, &dataStruct->y, 4);
memcpy(data + 32, &dataStruct->XSpeed, 4);
memcpy(data + 36, &dataStruct->YSpeed, 4);
memcpy(data + 44, &dataStruct->punchX, 4);
memcpy(data + 48, &dataStruct->punchY, 4);
return data;
}
void SendPacketRaw(int a1, void *packetData, size_t packetDataSize, void *a4, ENetPeer* peer, int packetFlag)
{
ENetPacket *p;
if (peer) // check if we have it setup
{
if (a1 == 4 && *((BYTE *)packetData + 12) & 8)
{
p = enet_packet_create(0, packetDataSize + *((DWORD *)packetData + 13) + 5, packetFlag);
int four = 4;
memcpy(p->data, &four, 4);
memcpy((char *)p->data + 4, packetData, packetDataSize);
memcpy((char *)p->data + packetDataSize + 4, a4, *((DWORD *)packetData + 13));
enet_peer_send(peer, 0, p);
}
else
{
p = enet_packet_create(0, packetDataSize + 5, packetFlag);
memcpy(p->data, &a1, 4);
memcpy((char *)p->data + 4, packetData, packetDataSize);
enet_peer_send(peer, 0, p);
}
}
delete (char*)packetData;
}
改成std::vector
后
std::vector<BYTE> packPlayerMoving(PlayerMoving *dataStruct)
{
std::vector<BYTE> data(56);
memcpy(&data[0], &dataStruct->packetType, 4);
memcpy(&data[4], &dataStruct->netID, 4);
memcpy(&data[12], &dataStruct->characterState, 4);
memcpy(&data[20], &dataStruct->plantingTree, 4);
memcpy(&data[24], &dataStruct->x, 4);
memcpy(&data[28], &dataStruct->y, 4);
memcpy(&data[32], &dataStruct->XSpeed, 4);
memcpy(&data[36], &dataStruct->YSpeed, 4);
memcpy(&data[44], &dataStruct->punchX, 4);
memcpy(&data[48], &dataStruct->punchY, 4);
return data;
}
void SendPacketRaw(int a1, std::vector<BYTE> packetData, size_t packetDataSize, void *a4, ENetPeer *peer, int packetFlag)
{
ENetPacket *p;
if (peer) // check if we have it setup
{
if (a1 == 4 && *(&packetData[12]) & 8)
{
p = enet_packet_create(0, packetDataSize + *(&packetData[13]) + 5, packetFlag);
int four = 4;
memcpy(p->data, &four, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
void * a4 = 0;
memcpy((char *)p->data + packetDataSize + 4, a4, *(&packetData[13]));
enet_peer_send(peer, 0, p);
}
else
{
p = enet_packet_create(0, packetDataSize + 5, packetFlag);
memcpy(p->data, &a1, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
enet_peer_send(peer, 0, p);
}
}
}
我是这样使用的：
SendPacketRaw(4, packPlayerMoving(&data), 56, 0, currentPeer, ENET_PACKET_FLAG_RELIABLE);
好的所以我的问题是在我将它转换为 std::vector 之前它工作正常没有问题
但是在我转换它之后我开始出现分段错误我做错了什么？
这里是 valgrind 输出
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x1189D7: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:172)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x1450E7: enet_packet_create (in /home/cmd/Desktop/PRC++/server)
==12418== by 0x118A20: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:174)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x48429FA: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x4842BA1: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x4842B0E: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Invalid read of size 2
==12418== at 0x4842B30: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==12418==
==12418==
==12418== Process terminating with default action of signal 11 (SIGSEGV)
==12418== Access not within mapped region at address 0x0
==12418== at 0x4842B30: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418== If you believe this happened as a result of a stack
==12418== overflow in your program's main thread (unlikely but
==12418== possible), you can try to increase the size of the
==12418== main thread stack using the --main-stacksize= flag.
==12418== The main thread stack size used in this run was 8388608.
==12418==
==12418== HEAP SUMMARY:
==12418== in use at exit: 11,557,918 bytes in 22,893 blocks
==12418== total heap usage: 94,578 allocs, 71,685 frees, 29,567,151 bytes allocated
==12418==
==12418== LEAK SUMMARY:
==12418== definitely lost: 1,312 bytes in 4 blocks
==12418== indirectly lost: 5,711 bytes in 17 blocks
==12418== possibly lost: 224 bytes in 2 blocks
==12418== still reachable: 11,550,671 bytes in 22,870 blocks
==12418== suppressed: 0 bytes in 0 blocks
==12418== Rerun with --leak-check=full to see details of leaked memory
==12418==
==12418== Use --track-origins=yes to see where uninitialised values come from
==12418== For lists of detected and suppressed errors, rerun with: -s
==12418== ERROR SUMMARY: 45563 errors from 34 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)
在您的原始代码中，在您的 SendPacketRaw() 函数中，您删除了传递给它的 packetData 指针参数，而在您的修改版本中，第二个参数 packetData是一个向量，它在函数结束后继续保存一些数据 SendPacketRaw().
我不确定你的 SendPacketRaw() 函数的使用以及管理它的第二个参数应该维护的内存的逻辑，但我有一种直觉，这是造成Valgrind 不高兴。
所以我建议您首先将第二个向量参数 packetData 作为参考传递，并在完成您的函数之前对其进行清理。
void SendPacketRaw(int a1, std::vector<BYTE> &packetData, size_t packetDataSize, void *a4, ENetPeer *peer, int packetFlag)
{
ENetPacket *p;
if (peer) // check if we have it setup
{
if (a1 == 4 && *(&packetData[12]) & 8)
{
p = enet_packet_create(0, packetDataSize + *(&packetData[13]) + 5, packetFlag);
int four = 4;
memcpy(p->data, &four, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
void * a4 = 0;
memcpy((char *)p->data + packetDataSize + 4, a4, *(&packetData[13]));
enet_peer_send(peer, 0, p);
}
else
{
p = enet_packet_create(0, packetDataSize + 5, packetFlag);
memcpy(p->data, &a1, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
enet_peer_send(peer, 0, p);
}
}
packetData.clear();
}
*((DWORD *)packetData + 13) 在您的第一个版本中读取第 13 个 DWORD（在字节索引 52 处）。
*(&packetData[13]) 在您的第二个版本中读取第 13 个字节。
整个代码有点乱，所以我不愿意只是掩盖这个问题，但将第二个版本更改为：
*(((DWORD *)packetData.data())+13) 应该修复它。
我想我在你的代码中发现了一个主要错误，一个 std::vector<BYTE> data ，在
&data[0]
如果你执行地址运算符，你会得到对象地址，因为 [] 是向量 class 的运算符。所以你可能想使用 data.data() 它会 return 你一个原始指针，在 memcpy()
之前做这个
ps: 我的第一个回答
你好，我有一个使用 new 关键字分配内存的结构，我想通过使用 std::vector 来删除，所以我这样做了
在更改为std::vector
之前BYTE* packPlayerMoving(PlayerMoving* dataStruct)
{
BYTE* data = new BYTE[56];
for (int i = 0; i < 56; i++)
{
data[i] = 0;
}
memcpy(data, &dataStruct->packetType, 4);
memcpy(data + 4, &dataStruct->netID, 4);
memcpy(data + 12, &dataStruct->characterState, 4);
memcpy(data + 20, &dataStruct->plantingTree, 4);
memcpy(data + 24, &dataStruct->x, 4);
memcpy(data + 28, &dataStruct->y, 4);
memcpy(data + 32, &dataStruct->XSpeed, 4);
memcpy(data + 36, &dataStruct->YSpeed, 4);
memcpy(data + 44, &dataStruct->punchX, 4);
memcpy(data + 48, &dataStruct->punchY, 4);
return data;
}
void SendPacketRaw(int a1, void *packetData, size_t packetDataSize, void *a4, ENetPeer* peer, int packetFlag)
{
ENetPacket *p;
if (peer) // check if we have it setup
{
if (a1 == 4 && *((BYTE *)packetData + 12) & 8)
{
p = enet_packet_create(0, packetDataSize + *((DWORD *)packetData + 13) + 5, packetFlag);
int four = 4;
memcpy(p->data, &four, 4);
memcpy((char *)p->data + 4, packetData, packetDataSize);
memcpy((char *)p->data + packetDataSize + 4, a4, *((DWORD *)packetData + 13));
enet_peer_send(peer, 0, p);
}
else
{
p = enet_packet_create(0, packetDataSize + 5, packetFlag);
memcpy(p->data, &a1, 4);
memcpy((char *)p->data + 4, packetData, packetDataSize);
enet_peer_send(peer, 0, p);
}
}
delete (char*)packetData;
}
改成std::vector
后std::vector<BYTE> packPlayerMoving(PlayerMoving *dataStruct)
{
std::vector<BYTE> data(56);
memcpy(&data[0], &dataStruct->packetType, 4);
memcpy(&data[4], &dataStruct->netID, 4);
memcpy(&data[12], &dataStruct->characterState, 4);
memcpy(&data[20], &dataStruct->plantingTree, 4);
memcpy(&data[24], &dataStruct->x, 4);
memcpy(&data[28], &dataStruct->y, 4);
memcpy(&data[32], &dataStruct->XSpeed, 4);
memcpy(&data[36], &dataStruct->YSpeed, 4);
memcpy(&data[44], &dataStruct->punchX, 4);
memcpy(&data[48], &dataStruct->punchY, 4);
return data;
}
void SendPacketRaw(int a1, std::vector<BYTE> packetData, size_t packetDataSize, void *a4, ENetPeer *peer, int packetFlag)
{
ENetPacket *p;
if (peer) // check if we have it setup
{
if (a1 == 4 && *(&packetData[12]) & 8)
{
p = enet_packet_create(0, packetDataSize + *(&packetData[13]) + 5, packetFlag);
int four = 4;
memcpy(p->data, &four, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
void * a4 = 0;
memcpy((char *)p->data + packetDataSize + 4, a4, *(&packetData[13]));
enet_peer_send(peer, 0, p);
}
else
{
p = enet_packet_create(0, packetDataSize + 5, packetFlag);
memcpy(p->data, &a1, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
enet_peer_send(peer, 0, p);
}
}
}
我是这样使用的：
SendPacketRaw(4, packPlayerMoving(&data), 56, 0, currentPeer, ENET_PACKET_FLAG_RELIABLE);
好的所以我的问题是在我将它转换为 std::vector 之前它工作正常没有问题 但是在我转换它之后我开始出现分段错误我做错了什么？
这里是 valgrind 输出
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x1189D7: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:172)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x1450E7: enet_packet_create (in /home/cmd/Desktop/PRC++/server)
==12418== by 0x118A20: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:174)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x48429FA: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x4842BA1: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Conditional jump or move depends on uninitialised value(s)
==12418== at 0x4842B0E: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418==
==12418== Invalid read of size 2
==12418== at 0x4842B30: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==12418==
==12418==
==12418== Process terminating with default action of signal 11 (SIGSEGV)
==12418== Access not within mapped region at address 0x0
==12418== at 0x4842B30: memmove (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==12418== by 0x118AA8: SendPacketRaw(int, std::vector<unsigned char, std::allocator<unsigned char> >, unsigned long, void*, _ENetPeer*, int) (utils.cpp:179)
==12418== by 0x11E337: Nothing(_ENetPeer*, int, int) (worlds.cpp:405)
==12418== by 0x1208AD: Events::Recieve(_ENetHost*, _ENetPacket*, _ENetPeer*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (events.cpp:315)
==12418== by 0x123BDB: Run() (main.cpp:62)
==12418== by 0x123C85: main (main.cpp:87)
==12418== If you believe this happened as a result of a stack
==12418== overflow in your program's main thread (unlikely but
==12418== possible), you can try to increase the size of the
==12418== main thread stack using the --main-stacksize= flag.
==12418== The main thread stack size used in this run was 8388608.
==12418==
==12418== HEAP SUMMARY:
==12418== in use at exit: 11,557,918 bytes in 22,893 blocks
==12418== total heap usage: 94,578 allocs, 71,685 frees, 29,567,151 bytes allocated
==12418==
==12418== LEAK SUMMARY:
==12418== definitely lost: 1,312 bytes in 4 blocks
==12418== indirectly lost: 5,711 bytes in 17 blocks
==12418== possibly lost: 224 bytes in 2 blocks
==12418== still reachable: 11,550,671 bytes in 22,870 blocks
==12418== suppressed: 0 bytes in 0 blocks
==12418== Rerun with --leak-check=full to see details of leaked memory
==12418==
==12418== Use --track-origins=yes to see where uninitialised values come from
==12418== For lists of detected and suppressed errors, rerun with: -s
==12418== ERROR SUMMARY: 45563 errors from 34 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)
在您的原始代码中，在您的 SendPacketRaw() 函数中，您删除了传递给它的 packetData 指针参数，而在您的修改版本中，第二个参数 packetData是一个向量，它在函数结束后继续保存一些数据 SendPacketRaw().
我不确定你的 SendPacketRaw() 函数的使用以及管理它的第二个参数应该维护的内存的逻辑，但我有一种直觉，这是造成Valgrind 不高兴。
所以我建议您首先将第二个向量参数 packetData 作为参考传递，并在完成您的函数之前对其进行清理。
void SendPacketRaw(int a1, std::vector<BYTE> &packetData, size_t packetDataSize, void *a4, ENetPeer *peer, int packetFlag)
{
ENetPacket *p;
if (peer) // check if we have it setup
{
if (a1 == 4 && *(&packetData[12]) & 8)
{
p = enet_packet_create(0, packetDataSize + *(&packetData[13]) + 5, packetFlag);
int four = 4;
memcpy(p->data, &four, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
void * a4 = 0;
memcpy((char *)p->data + packetDataSize + 4, a4, *(&packetData[13]));
enet_peer_send(peer, 0, p);
}
else
{
p = enet_packet_create(0, packetDataSize + 5, packetFlag);
memcpy(p->data, &a1, 4);
memcpy((char *)p->data + 4, &packetData[0], packetDataSize);
enet_peer_send(peer, 0, p);
}
}
packetData.clear();
}
*((DWORD *)packetData + 13) 在您的第一个版本中读取第 13 个 DWORD（在字节索引 52 处）。
*(&packetData[13]) 在您的第二个版本中读取第 13 个字节。
整个代码有点乱，所以我不愿意只是掩盖这个问题，但将第二个版本更改为：
*(((DWORD *)packetData.data())+13) 应该修复它。
我想我在你的代码中发现了一个主要错误，一个 std::vector<BYTE> data ，在
&data[0]
如果你执行地址运算符，你会得到对象地址，因为 [] 是向量 class 的运算符。所以你可能想使用 data.data() 它会 return 你一个原始指针，在 memcpy()
之前做这个
ps: 我的第一个回答