C++ 删除动态对象时出错？

我正在为堆中的union分配内存，当union的元素Id为900时，我需要删除union的对象

Id为900时，请帮助我删除groupUnion[i]对象 下面是我的代码

groupUnion = (SettingsUnion *) malloc(sizeof(SettingsUnion) * (NumAttrs + 1));
if(groupUnion == (SettingsUnion *) NULL)
{
    return (FALSE);
}

for (unsigned int i=0; i < NumAttrs; i++)
{
    inFile.read(reinterpret_cast<char*>(&groupUnion[i]),sizeof(SettingsUnion));
    if(groupUnion[i].Id == 900)
    {
        free groupUnion[i]; // this is bad how can i delete groupUnion[i] when groupUnion[i].Id == 900
        groupUnion[i] = NULL;
    }
}

inFile.close()

提前谢谢

您的代码片段自由groupUnion[i]；groupUnion[i]=NULL允许我假设您实际上想要表示指向SettingUnion对象的指针数组，而不是SettingUnion对象数组。 所以你的代码看起来就像我使用了你的MalC/Cype风格，但是在C++中你实际上会使用NeX/DELL:

---

无法释放部分已分配内存：free groupUnion[i]

但是，您可以单独分配元素，然后单独释放它们：

// not sure why you need the +1 (anyway you allocate an array of pointers to the struct here. Consider using new operator)
groupUnion = (SettingsUnion **) malloc(sizeof(SettingsUnion *) * (NumAttrs + 1)); 
if(groupUnion == (SettingsUnion *) NULL)
{
    return (FALSE);
}

for (unsigned int i=0; i < NumAttrs; i++)
{
    // you allocate the individual groupUnion here:
    groupUnion[i] = (SettingsUnion *) malloc(sizeof(SettingsUnion));
    if(groupUnion[i] == (SettingsUnion *) NULL)
    {
        return (FALSE);
    }

    inFile.read(reinterpret_cast<char*>(&groupUnion[i]),sizeof(SettingsUnion));
   if(groupUnion[i].Id == 900)
   {
        free groupUnion[i]; // this is bad how can i delete groupUnion[i] when groupUnion[i].Id == 900
        groupUnion[i] = NULL;
   }
}

inFile.close()

---

不能在已分配内存的中间分配一段内存。然而，我非常怀疑这是你想要的——如果你释放一段内存，你就不能再访问它了，所以你就不能知道它的Id==900。你真正想做什么？如何做到这一点。不要在C++中使用MalC/C。使用向量、唯一\u ptr、使\u唯一、新建/删除。

// not sure why you need the +1 (anyway you allocate an array of pointers to the struct here. Consider using new operator)
groupUnion = (SettingsUnion **) malloc(sizeof(SettingsUnion *) * (NumAttrs + 1)); 
if(groupUnion == (SettingsUnion *) NULL)
{
    return (FALSE);
}

for (unsigned int i=0; i < NumAttrs; i++)
{
    // you allocate the individual groupUnion here:
    groupUnion[i] = (SettingsUnion *) malloc(sizeof(SettingsUnion));
    if(groupUnion[i] == (SettingsUnion *) NULL)
    {
        return (FALSE);
    }

    inFile.read(reinterpret_cast<char*>(&groupUnion[i]),sizeof(SettingsUnion));
   if(groupUnion[i].Id == 900)
   {
        free groupUnion[i]; // this is bad how can i delete groupUnion[i] when groupUnion[i].Id == 900
        groupUnion[i] = NULL;
   }
}

inFile.close()