Are there gotchas using varargs with reference parameters
- by Roddy
I have this piece of code (summarized)...
AnsiString working(AnsiString format,...)
{
va_list argptr;
AnsiString buff;
va_start(argptr, format);
buff.vprintf(format.c_str(), argptr);
va_end(argptr);
return buff;
}
And, on the basis that pass by reference is preferred where possible, I changed it thusly.
AnsiString broken(const AnsiString &format,...)
{
... the rest, totally identical ...
}
My calling code is like this:-
AnsiString s1, s2;
s1 = working("Hello %s", "World");
s2 = broken("Hello %s", "World");
But, s1 contains "Hello World", while s2 has "Hello (null)". I think this is due to the way va_start works, but I'm not exactly sure what's going on.
