c++ - 如何正确删除那些指针？

Question

这是我的分配:

for (int i = 0; i < numCols; i++)
{
    columnNameLen = new SQLSMALLINT *[numCols];
    columnDataType = new SQLSMALLINT *[numCols];
    columnDataSize = new SQLULEN *[numCols];
    columnDataDigits = new SQLSMALLINT *[numCols];
    columnDataNullable = new SQLSMALLINT *[numCols];
    columnData = new SQLWCHAR *[numCols];
    columnDataLen = new SQLLEN *[numCols];
    columnName = new SQLWCHAR *[numCols];
}

for (int i = 0; i < numCols; i++)
{
    columnNameLen[i] = new SQLSMALLINT;
    columnDataType[i] = new SQLSMALLINT;
    columnDataSize[i] = new SQLULEN;
    columnDataDigits[i] = new SQLSMALLINT;
    columnDataNullable[i] = new SQLSMALLINT;
    columnDataLen[i] = new SQLLEN;
    columnName[i] = new SQLWCHAR[256];
}

这是我的删除:

for (int i = 0; i < numCols; i++)
{
    delete columnNameLen[i];
    columnNameLen[i] = NULL;
    delete columnDataType[i];
    columnDataType[i] = NULL;
    delete columnDataSize[i];
    columnDataSize[i] = NULL;
    delete columnDataDigits[i];
    columnDataDigits[i] = NULL;
    delete columnDataNullable[i];
    columnDataNullable[i] = NULL;
    delete columnData[i];
    columnData[i] = NULL;
    delete columnDataLen[i];
    columnDataLen[i] = NULL;
    delete[] columnName[i];
    columnName[i] = NULL;
}

for (int i = 0; i < numCols; i++)
{
    delete[] columnNameLen;
    columnNameLen = NULL;
    delete[] columnDataType;
    columnDataType = NULL;
    delete[] columnDataSize;
    columnDataSize = NULL;
    delete[] columnDataDigits;
    columnDataDigits = NULL;
    delete[] columnDataNullable;
    columnDataNullable = NULL;
    delete[] columnData;
    columnData = NULL;
    delete[] columnDataLen;
    columnDataLen = NULL;
    delete[] columnName;
    columnName = NULL;
}

上面的代码可以吗？我可能应该只使用智能指针，但我不知道使用它们后代码会是什么样子？因此，如果您输入智能指针代码，我们将不胜感激。这些指针在线程函数中本地使用，不与任何东西共享。

我担心第二个循环只需要 delete 而不是 delete[]。

TIA!

Answer 1

你不应该在这里使用指针根本。

using SQLSTRING = std::basic_string<SQLWCHAR>;

struct Column
{
    SQLSTRING Name;
    SQLSTRING Data;
    SQLSMALLINT DataType;
    SQLULEN DataSize;
    SQLSMALLINT DataDigits;
    SQLSMALLINT DataNullable;
}

std::vector<Column> columns(numCols);