Specialized::StringCollection^ combinations = gcnew Specialized::StringCollection;

for each(int number in numbers)
for each(String^ letter in letters)
combinations->Add(makeCombo(letter, number));

using namespace System;
using namespace System::Collections;

String^ makeCombo(String^ letter, int number, String^ sep = ",") { return letter + sep + Convert::ToString(number); }

int main()
{
array<String^>^ letters = {"a", "b", "c"}; array<int>^ numbers = {4, 5};

Specialized::StringCollection^ combinations = gcnew Specialized::StringCollection;

for each(int number in numbers)
for each(String^ letter in letters)
combinations->Add(makeCombo(letter, number));

for each(String^ item in combinations) Console::Write("{0} ", item);
}

string letters[] = { "a", "b", "c" };
int numbers[] = { 4, 5 };
list<pair<string,int> > combo;

for (int n = 0; n < sizeof numbers / sizeof *numbers; n++)
for (int l = 0; l < sizeof letters / sizeof *letters; l++)
combo.push_back(make_pair(letters[l], numbers[n]));

cout << combo << endl;

#include <iostream>
#include <list>
#include <string>

using namespace std;

ostream& operator<<(ostream &os, const pair<string, int> &p)
{
os << "[ \"" << p.first << "\", " << p.second << "]";
return os;
}

template<typename T>
ostream& operator<<(ostream &os, const list<T> &l)
{
string sep;

os << "[";
for (typename list<T>::const_iterator it = l.begin(); it != l.end(); ++it)
{
os << sep << *it;
sep = ", ";
}
os << "]";
return os;
}

int main()
{
string letters[] = { "a", "b", "c" };
int numbers[] = { 4, 5 };
list<pair<string,int> > combo;

for (int n = 0; n < sizeof numbers / sizeof *numbers; n++)
for (int l = 0; l < sizeof letters / sizeof *letters; l++)
combo.push_back(make_pair(letters[l], numbers[n]));

cout << combo << endl;
}