Question on using for_each

[Yan]

I have a vector of elements which I iterate through and call a method
on each of the elements. I want to do it using std::for_each
algorithm, but having a problem implementing it since the method that
I call on each element takes an argument and I don't know how to pass
this argument through. Here is the code using an old fashioned loop:

.......
std::vector<uns igned char bytes;
std::vector<Tel ements;
....
for (int i = 0; i < elements.size() ; ++i) {
elements[i].serialize(byte s);
}
..........

could someone please help me out rewrite that using std::for_each?

Thanks!

[Barry]

Re: Question on using for_each

On 11ÔÂ6ÈÕ, ÏÂÎç10ʱ47·Ö, Yan <yvinogra...@gm ail.comwrote:

I have a vector of elements which I iterate through and call a method
on each of the elements. I want to do it using std::for_each
algorithm, but having a problem implementing it since the method that
I call on each element takes an argument and I don't know how to pass
this argument through. Here is the code using an old fashioned loop:
>
......
std::vector<uns igned char bytes;
std::vector<Tel ements;
...
for (int i = 0; i < elements.size() ; ++i) {
elements[i].serialize(byte s);}
>
.........
>
could someone please help me out rewrite that using std::for_each?
>

struct Op
{
Op(std::vector< unsigned char>& bytes)
: bytes_(&bytes)
{}

void operator() (T& t)
{
t.serialize(*by tes_);
}

private:
std::vector<uns igned char>* bytes_;
};

std::for_each(e lements.begin() , elements.end(), Op(bytes));

--
Best Regards
Barry

[Maxim Yegorushkin]

Re: Question on using for_each

On Nov 6, 2:47 pm, Yan <yvinogra...@gm ail.comwrote:

I have a vector of elements which I iterate through and call a method
on each of the elements. I want to do it using std::for_each
algorithm, but having a problem implementing it since the method that
I call on each element takes an argument and I don't know how to pass
this argument through. Here is the code using an old fashioned loop:
>
......
std::vector<uns igned char bytes;
std::vector<Tel ements;
...
for (int i = 0; i < elements.size() ; ++i) {
  elements[i].serialize(byte s);}
>
.........
>
could someone please help me out rewrite that using std::for_each?

It may be better to use a straight forward loop, because this way it
is much more easier to read and debug than for_each loops with complex
functors.

Compare your loop with:

std::for_each(e lements.begin() , elements.end(),
boost::bind(&T: :serialize, _1, boost::ref(byte s)));

--
Max

[sean_in_raleigh@yahoo.com]

Re: Question on using for_each

On Nov 6, 9:47 am, Yan <yvinogra...@gm ail.comwrote:

I have a vector of elements which I iterate through and call a method
on each of the elements. I want to do it using std::for_each
algorithm, but having a problem implementing it since the method that
I call on each element takes an argument and I don't know how to pass
this argument through. Here is the code using an old fashioned loop:
>
......
std::vector<uns igned char bytes;
std::vector<Tel ements;
...
for (int i = 0; i < elements.size() ; ++i) {
elements[i].serialize(byte s);}
>
.........
>
could someone please help me out rewrite that using std::for_each?
>
Thanks!

Here's the standard-C++ way, though the boost::bind method
mentioned earlier is more flexible.

class MySerializable
{
public:
void serialize(vecto r<unsigned char*b)
{
b->push_back(my_b its);
}
private:
unsigned char my_bits;
};

int
main(int argc, char **argv)
{
vector<unsigned char bytes;
vector<MySerial izableelements;

// ... fill in elements ...

for_each(elemen ts.begin(), elements.end(),
bind2nd(mem_fun _ref(&MySeriali zable::serializ e),
&bytes));
}

Sean

[Yan]

Re: Question on using for_each

On Nov 6, 11:35 am, sean_in_rale... @yahoo.com wrote:

On Nov 6, 9:47 am, Yan <yvinogra...@gm ail.comwrote:
>
>
>

I have a vector of elements which I iterate through and call a method
on each of the elements. I want to do it using std::for_each
algorithm, but having a problem implementing it since the method that
I call on each element takes an argument and I don't know how to pass
this argument through. Here is the code using an old fashioned loop:

>

......
std::vector<uns igned char bytes;
std::vector<Tel ements;
...
for (int i = 0; i < elements.size() ; ++i) {
  elements[i].serialize(byte s);}

>

.........

>

could someone please help me out rewrite that using std::for_each?

>

Thanks!

>
Here's the standard-C++ way, though the boost::bind method
mentioned earlier is more flexible.
>
class MySerializable
{
public:
    void serialize(vecto r<unsigned char*b)
    {
        b->push_back(my_b its);
    }
private:
    unsigned char my_bits;
>
};
>
int

Thanks everyone!

Indeed, in this case the good old loop seems easier to write, read,
and, if needed, to debug :)

main(int argc, char **argv)
{
    vector<unsigned char bytes;
    vector<MySerial izableelements;
>
    // ... fill in elements ...
>
    for_each(elemen ts.begin(), elements.end(),
             bind2nd(mem_fun _ref(&MySeriali zable::serializ e),
&bytes));
>
}
>
Sean