std :: vector和_variant_t之间的转换 [英] conversion between std::vector and _variant_t

问题描述

我需要在 std :: vector 和 _variant_t 之间进行转换，以避免在将数据写入/文件（数据库，Excel等）

I need to convert between std::vector and _variant_t to avoid looping when writing/sending data into some file (database, Excel, etc.)

能否让我知道如何处理？

Could you please let me know how to proceed with that?

我试图得到一个 std :: vector< _variant_t> 并以某种方式放入另一个 _variant_t 变量，不支持转换，即使它完成，也没有任何方法或某种包装器将此向量转换为 _variant_t 变量。

I was trying to get a std::vector<_variant_t> and somehow put into another _variant_t variable, but direct conversion is not supported and even if it's done there's no either method or some kind of wrapper to get this vector into a _variant_t variable.

我不想处理任何循环。

推荐答案

A std ::向量和 _variant_t 是不兼容的类型。 _variant_t 类型旨在支持COM接口需要支持相同参数的多种类型的值的情况。它的值集合仅限于COM了解如何编组。 std :: vectory 不是这些类型之一。

A std::vector and _variant_t are incompatible types. The _variant_t type is designed to support scenarios where a COM interface needs to support multiple types of values for the same parameters. It's set of values is limited to those for which COM understands how to marshal. std::vectory is not one of those types.

_variant_t 是一个安全的数组。因此，最简单的解决方案是将 std :: vector 转换为安全数组，并将其存储在变体中。这里真的没有办法避免一个循环

The standard way to store a collection of values into a _variant_t is to do so as a safe array. So the easiest solution is to convert the std::vector to a safe array and store that in the variant. There's really no way to avoid a loop here

// Convert to a safe array
CComSafeArary<INT> safeArray;
std::vector<int> col = ...;
for (std::vector<int>::const_iteator it = col.begin(); it != col.end(); it++) {
  safeArray.Add(*it);
}

// Initialize the variant
VARIANT vt;
VariantInit(&vt);
vt.vt = VT_ARRAY | VT_INT;
vt.parray = safeArray.Detach();

// Create the _variant_t
_variant_t variant;
variant.Attach(vt);

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