function(...)

It's for functions with variable length parameters. For example, C's printf lets you pass however many parameters you want to it.

The ellipsis indicates the function can accept a variable number of parameters. Such functions universally rely on the va_start, va_arg and va_end macros (google for details), which essentially let them grab arbitrary blocks of data off the stack (where the function parameters are located). The function relies on its first parameter (here, the format string) to figure out how many parameters are to be read, and what their types are. No checking is done, so if you try to read the wrong number or the wrong types of parameters, all you get is garbage.

thnx guys :)

As an side:

Many (not all, nor necessairly the majority even - but still many) programmers consider variable length arguments like this to be shoddy programming - no type safety, and the results are undefined if you try to pass a class to the function as one of the variable arguments.

There are alternatives (at least in C++), such as operator chaining. Example from the boost library:

//Replacing printf(...):#include <boost/format.hpp>#include <iostream>using namespace std;using namespace boost;cout << format("%1% %2% %3%") % "I" % "like" % "pie" << endl;//It also works with functions that expect simple strings:#include <string>void function( const string & );function( str( format("%1% %2% %3%") % "I" % "love" % "rootbeer" ) );

Another utility of the boost library that may prove useful:

#include <boost/assign/list_inserter.hpp> // for 'insert()'#include <boost/assert.hpp> #include <string>using namespace std;using namespace boost::assign; // bring 'insert()' into scope {    map<string,int> months;      insert( months )        ( "january",   31 )( "february", 28 )        ( "march",     31 )( "april",    30 )        ( "may",       31 )( "june",     30 )        ( "july",      31 )( "august",   31 )        ( "september", 30 )( "october",  31 )        ( "november",  30 )( "december", 31 );    BOOST_ASSERT( months.size() == 12 );        BOOST_ASSERT( months["january"] == 31 );}