Tom Hines (writinThatCode.com)

Here is another example taken (slightly) directly from the MSDN page concerning Enumerable::SelectMany.
This example is in C++/CLI and appears to be missing from the list of examples.

// MSDN_bb534336_CPP.cpp : main project file.
// https://msdn.microsoft.com/en-us/library/vstudio/bb534336(v=vs.100).aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-2
#include "stdafx.h"
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Linq;
 
public ref class PetOwner
{
private:
	static List<String^>^ GetPets(PetOwner^ petOwner) { return petOwner->Pets;	}
	static IEnumerable<String^>^ GetListAsArray(List<String^>^ lst) { return lst; }
	static IEnumerable<String^>^ GetArrayAsArray(IEnumerable<String^>^ arr) { return arr; }
 
public:
	property String^ Name;
	property List<String^>^ Pets;
 
	PetOwner(String^ Name, List<String^>^ Pets)
	{
		this->Name = Name;
		this->Pets = Pets;
	}
 
	static Func<PetOwner^, List<String^>^>^ getPets = gcnew Func<PetOwner^, List<String^>^>(GetPets);
	static Func<List<String^>^, IEnumerable<String^>^>^ getListAsArray = gcnew Func<List<String^>^, IEnumerable<String^>^>(GetListAsArray);
	static Func<IEnumerable<String^>^, IEnumerable<String^>^>^ getArrayAsArray = gcnew Func<IEnumerable<String^>^, IEnumerable<String^>^>(GetArrayAsArray);
};
 
static void SelectManyEx1()
{
	array<PetOwner^, 1>^ petOwners =
	{
		gcnew PetOwner("Higa, Sidney", Enumerable::ToList<String^>(gcnew array < String^, 1 > { "Scruffy", "Sam" })),
		gcnew PetOwner("Ashkenazi, Ronen", Enumerable::ToList<String^>(gcnew array < String^, 1 > { "Walker", "Sugar" })),
		gcnew PetOwner("Price, Vernette", Enumerable::ToList<String^>(gcnew array < String^, 1 > { "Scratches", "Diesel" }))
	};
 
	// Query using SelectMany().
	IEnumerable<List<String^>^>^ query3 =
		Enumerable::Select<PetOwner^, List<String^>^>
		(	// extract List of String^ from PetOwners
			petOwners, PetOwner::getPets
		);
 
	// This code shows how to use Select() 
	// instead of SelectMany().
 
	Console::WriteLine("\nUsing Select():");
	// Notice that two foreach loops are required to 
	// iterate through the results
	// because the query returns a collection of arrays.
	for each(List<String^>^ petList in query3)
	{
		for each(String^ pet in petList)
		{
			Console::WriteLine(pet);
		}
 
		Console::WriteLine();
	}
 
	IEnumerable<IEnumerable<String^>^>^ query2 =
		Enumerable::Select<List<String^>^, IEnumerable<String^>^>
		(	// convert List of String^ to IEnumerable of String^
			query3, PetOwner::getListAsArray
		);
 
	Console::WriteLine("Using SelectMany():");
	IEnumerable<String^>^ query1 =
		Enumerable::SelectMany<IEnumerable<String^>^, String^>
		(	// extract IENumerable of String^ from embedded IEnumerable
			query2, PetOwner::getArrayAsArray
		);
 
	// Only one foreach loop is required to iterate 
	// through the results since it is a
	// one-dimensional collection.
	for each(String^ pet in query1)
	{
		Console::WriteLine(pet);
	}
 
		/*
		This code produces the following output:
 
			Using Select():
			Scruffy
			Sam
 
			Walker
			Sugar
 
			Scratches
			Diesel
 
			Using SelectMany():
			Scruffy
			Sam
			Walker
			Sugar
			Scratches
			Diesel
		*/
}