## CustomXmlPropertyCol::IndexOfKey method Returns the zero-based index of the specified property in the collection. ```cpp int32_t Aspose::Words::Markup::CustomXmlPropertyCol::IndexOfKey(const Sys......doc->GetChildNodes(NodeType::SmartTag, true)->LINQ_OfType<System::SharedPtr<As...ords::Markup::SmartTag>>()->LINQ_ToArray(); ASSERT_EQ(8, sma...