Create va_list dynamically

Question

I have a function

void foo(int cnt, va_list ap);

I need to use it, but requirement is quite strict, number of va_list vary an

Answer 1

...hmmm...maybe not portable...for sure not nice...but may solve yor problem...

• va_list is (at least for visual c++) just a #define for char*
• → arguments don't need to be on the stack
• → arguments are just required to be continuous in memory
• → no need to use assembler and/or copying (see my 'just for fun answer' :-)
• → no need to worry about cleanup
• efficient!
• tested on w2k3 sp2 32bit + vc++ 2010

#include 
#include 
#include 
#include 

#define N 6 // test argument count

void foo(int n, va_list args);

int main(int, char*[])
{
    std::vector strings;
    std::wstring s(L"a");
    int i(0);

    // create unique strings...
    for (; i != N; ++i)
    {
        strings.push_back(s);
        ++s.front();
    }
    foo(N, reinterpret_cast(strings.data()));
    return 0;
}

void foo(int n, va_list args)
{
    int i(0);

    for (; i != n; ++i)
        std::wcout << va_arg(args, std::wstring) << std::endl;
}