c++ - call of overloaded *** <unresolved overloaded function type>)' is ambiguous -

please me how resolve error

template <typename inputlterator, typename outputlterator, typename predicate> outputlterator copy_if( inputlterator begin, inputlterator end, outputlterator destbegin, predicate p)  {     return remove_copy_if(begin, end,destbegin, not1( ptr_fun( p ) ) ); } template <class t> bool is_not_3( t val ) {     return val != 3; } void foo( ) {     vector<int> v;     v.push_back( 1 );     v.push_back( 2 );     v.push_back( 3 );     copy_if( v.begin( ), v.end( ), ostream_iterator<int>( cout, " " ), is_not_3<int> ); } 

and error saying : error: call of overloaded 'copy_if(std::vector::iterator, std::vector::iterator, std::ostream_iterator, )' ambiguous

rewrite statement

copy_if( v.begin( ), v.end( ), ostream_iterator<int>( cout, " " ), //...); 

like

::copy_if( v.begin( ), v.end( ), ostream_iterator<int>( cout, " " ), //...); ^^^ 

otherwise function conflicts standard algorithm std::copy_if

the problem arised due using derictive

using namespace std; 

pay attention function call in code snippet not syntaxically finished. forgot specify last argument.