using lambda as function argument.
Heres a simple question, that i want to do. Lets say you have a function call void f(double); and then you want to apply f to each argument inside vector<double> a; for_each(a.begin(), a.end(), f(_1)); // the example above isn't possible..is there a simple way to do this?
"chun ping wang" <cablepuff@gmail.com> writes:
Heres a simple question, that i want to do.
Lets say you have a function call void f(double);
and then you want to apply f to each argument inside vector<double> a;
for_each(a.begin(), a.end(), f(_1));
// the example above isn't possible..is there a simple way to do this?
for_each(a.begin(), a.end(), bind(f, _1)); HTH, -- Dave Abrahams Boost Consulting www.boost-consulting.com
For some reason this thing don't work. I want to print a container of container..... #ifndef ARRAY_OPERATION_HPP #define ARRAY_OPERATION_HPP #include <iostream> #include <boost/lambda/lambda.hpp> template <typename T, template < typename ELEM, typename = std::allocator<ELEM> > class CONT
void print_array(const CONT<T>& array) { using namespace boost::lambda; std::for_each(array.begin(), array.end(), std::cout << _1 << " "); } template <typename T, template < typename ELEM, typename = std::allocator<ELEM> > class CONT
void print_2darray (const CONT<CONT<T> >& array) { using namespace boost::lambda; CONT<T> temp; std::for_each(array.begin(), array.end(), bind<T, CONT>(print_array<T, CONT>(), _1) ); } #endif /* ARRAY_OPERATION_HPP */ if i have std::list<std::list<double> > lOflDouble // insert some value in here. print_2darray<double>(lOflDouble); /* 30 C:\cs classes\cs540\c++\ContainerOperation.hpp no matching function for call to `print_array()' */ On 4/14/06, David Abrahams <dave@boost-consulting.com> wrote:
"chun ping wang" <cablepuff@gmail.com> writes:
Heres a simple question, that i want to do.
Lets say you have a function call void f(double);
and then you want to apply f to each argument inside vector<double> a;
for_each(a.begin(), a.end(), f(_1));
// the example above isn't possible..is there a simple way to do this?
for_each(a.begin(), a.end(), bind(f, _1));
HTH,
-- Dave Abrahams Boost Consulting www.boost-consulting.com
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
k ignore hte previous example..i figure out a way around that using BOOST_FOREACH.... Operator- version 1 works. template <typename T, template <typename ELEM, typename = std::allocator<ELEM> > class CONT
CONT<T> operator-(CONT<T> arr1, CONT<T> arr2) { using namespace boost::lambda; typedef typename CONT<T>::size_type sz; const sz arr1Size(arr1.size()); const sz arr2Size(arr2.size()); BOOST_STATIC_ASSERT(arr1Size == arr2Size); std::transform(arr1.begin(), arr1.end(), arr2.begin(), arr1.end(), _1 -= _2); return arr1; } operator version 2: does not work. template <typename T, template <typename ELEM, typename = std::allocator<ELEM> > class CONT
CONT<CONT<T> > operator-(CONT<CONT<T> > arr1, CONT<CONT<T> > arr2) { using namespace boost::lambda; std::transform(arr1.begin(), arr1.end(), arr2.begin(), arr1.end(), protect(_1 - _2)); return arr1; } Heres hte error i get. 826 C:\Dev-Cpp\include\c++\3.4.2\bits\stl_algo.h no match for 'operator=' in '(&__result)->__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = std::vector<long int, std::allocator<long int> >*, _Container = std::vector<std::vector<long int, std::allocator<long int> >, std::allocator<std::vector<long int, std::allocator<long int> > > >]() = boost::lambda::lambda_functor<Base>::operator()(A&, B&) const [with A = std::vector<long int, std::allocator<long int> >, B = std::vector<long int, std::allocator<long int> >, T = boost::lambda::lambda_functor_base<boost::lambda::protect_action, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::minus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>
, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >](((std::vector<long int, std::allocator<long int> >&)(+(&__first1)->__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = std::vector<long int, std::allocator<long int> >*, _Container = std::vector<std::vector<long int, std::allocator<long int> >, std::allocator<std::vector<long int, std::allocator<long int> > > >]())), ((std::vector<long int, std::allocator<long int> &)(+(&__first2)->__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = std::vector<long int, std::allocator<long int> >*, _Container = std::vector<std::vector<long int, std::allocator<long int> >, std::allocator<std::vector<long int, std::allocator<long int> > > >]())))'
note C:\Dev-Cpp\include\c++\3.4.2\bits\vector.tcc:131 candidates are: std::vector<T, Allocator>& std::vector<T, Allocator>::operator=(const std::vector<T, Allocator>&) [with _Tp = long int, _Alloc = std::allocator<long int>] anyone care to explain how to fix these errors? Thanks. On 4/14/06, chun ping wang <cablepuff@gmail.com> wrote:
For some reason this thing don't work. I want to print a container of container.....
#ifndef ARRAY_OPERATION_HPP #define ARRAY_OPERATION_HPP #include <iostream> #include <boost/lambda/lambda.hpp>
template <typename T, template < typename ELEM, typename = std::allocator<ELEM> > class CONT
void print_array(const CONT<T>& array) { using namespace boost::lambda; std::for_each(array.begin(), array.end(), std::cout << _1 << " "); }
template <typename T, template < typename ELEM, typename = std::allocator<ELEM> > class CONT
void print_2darray (const CONT<CONT<T> >& array) { using namespace boost::lambda; CONT<T> temp; std::for_each(array.begin(), array.end(), bind<T, CONT>(print_array<T, CONT>(), _1) ); }
#endif /* ARRAY_OPERATION_HPP */
if i have std::list<std::list<double> > lOflDouble
// insert some value in here.
print_2darray<double>(lOflDouble);
/* 30 C:\cs classes\cs540\c++\ContainerOperation.hpp no matching function for call to `print_array()' */
On 4/14/06, David Abrahams <dave@boost-consulting.com> wrote:
"chun ping wang" <cablepuff@gmail.com> writes:
Heres a simple question, that i want to do.
Lets say you have a function call void f(double);
and then you want to apply f to each argument inside vector<double> a;
for_each(a.begin(), a.end(), f(_1));
// the example above isn't possible..is there a simple way to do this?
for_each(a.begin(), a.end(), bind(f, _1));
HTH,
-- Dave Abrahams Boost Consulting www.boost-consulting.com
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
so does anyone know how to fix previous error above? On 4/15/06, chun ping wang <cablepuff@gmail.com> wrote:
k ignore hte previous example..i figure out a way around that using BOOST_FOREACH....
Operator- version 1 works.
template <typename T, template <typename ELEM, typename = std::allocator<ELEM> > class CONT
CONT<T> operator-(CONT<T> arr1, CONT<T> arr2) { using namespace boost::lambda; typedef typename CONT<T>::size_type sz; const sz arr1Size(arr1.size()); const sz arr2Size(arr2.size()); BOOST_STATIC_ASSERT(arr1Size == arr2Size); std::transform(arr1.begin(), arr1.end(), arr2.begin(), arr1.end(), _1 -= _2); return arr1; }
operator version 2: does not work.
template <typename T, template <typename ELEM, typename = std::allocator<ELEM> > class CONT
CONT<CONT<T> > operator-(CONT<CONT<T> > arr1, CONT<CONT<T> > arr2) { using namespace boost::lambda; std::transform(arr1.begin(), arr1.end(), arr2.begin(), arr1.end(), protect(_1 - _2)); return arr1; }
Heres hte error i get. 826 C:\Dev-Cpp\include\c++\3.4.2\bits\stl_algo.h no match for 'operator=' in '(&__result)->__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = std::vector<long int, std::allocator<long int> >*, _Container = std::vector<std::vector<long int, std::allocator<long int> >, std::allocator<std::vector<long int, std::allocator<long int> > > >]() = boost::lambda::lambda_functor<Base>::operator()(A&, B&) const [with A = std::vector<long int, std::allocator<long int> >, B = std::vector<long int, std::allocator<long int> >, T = boost::lambda ::lambda_functor_base<boost::lambda::protect_action, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda ::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::minus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>
, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >](((std::vector<long int, std::allocator<long int> >&)(+(&__first1)->__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = std::vector<long int, std::allocator<long int> >*, _Container = std::vector<std::vector<long int, std::allocator<long int> >, std::allocator<std::vector<long int, std::allocator<long int> > > >]())), ((std::vector<long int, std::allocator<long int> &)(+(&__first2)->__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = std::vector<long int, std::allocator<long int> >*, _Container = std::vector<std::vector<long int, std::allocator<long int> >, std::allocator<std::vector<long int, std::allocator<long int> > > >]())))'
note C:\Dev-Cpp\include\c++\3.4.2\bits\vector.tcc:131 candidates are: std::vector<T, Allocator>& std::vector<T, Allocator>::operator=(const std::vector<T, Allocator>&) [with _Tp = long int, _Alloc = std::allocator<long int>]
anyone care to explain how to fix these errors? Thanks.
On 4/14/06, chun ping wang <cablepuff@gmail.com> wrote:
For some reason this thing don't work. I want to print a container of container.....
#ifndef ARRAY_OPERATION_HPP #define ARRAY_OPERATION_HPP #include <iostream> #include <boost/lambda/lambda.hpp>
template <typename T, template < typename ELEM, typename = std::allocator<ELEM> > class CONT
void print_array(const CONT<T>& array) { using namespace boost::lambda; std::for_each(array.begin(), array.end(), std::cout << _1 << " "); }
template <typename T, template < typename ELEM, typename = std::allocator<ELEM> > class CONT
void print_2darray (const CONT<CONT<T> >& array) { using namespace boost::lambda; CONT<T> temp; std::for_each(array.begin(), array.end(), bind<T, CONT>(print_array<T, CONT>(), _1) ); }
#endif /* ARRAY_OPERATION_HPP */
if i have std::list<std::list<double> > lOflDouble
// insert some value in here.
print_2darray<double>(lOflDouble);
/* 30 C:\cs classes\cs540\c++\ContainerOperation.hpp no matching function for call to `print_array()' */
On 4/14/06, David Abrahams < dave@boost-consulting.com> wrote:
"chun ping wang" <cablepuff@gmail.com> writes:
Heres a simple question, that i want to do.
Lets say you have a function call void f(double);
and then you want to apply f to each argument inside vector<double> a;
for_each(a.begin(), a.end(), f(_1));
// the example above isn't possible..is there a simple way to do this?
for_each(a.begin(), a.end(), bind(f, _1));
HTH,
-- Dave Abrahams Boost Consulting www.boost-consulting.com
_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
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David Abrahams