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Jens
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 Posted: Thu Oct 28, 2004 9:39 am Post subject: objectStream in C++? |
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Hi
Is there at class in C++ to make objectstreams or shall I make it yourself?
Thanks
Jens
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Catalin Pitis
Guest
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| Posted: Thu Oct 28, 2004 9:57 am Post subject: Re: objectStream in C++? |
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"Jens" <jens.cortsenremovethiis (AT) tiscali (DOT) dk> wrote
| Quote: | Hi
Is there at class in C++ to make objectstreams or shall I make it
yourself?
Thanks
Jens
|
A common solution is to define streaming operators for stream in and out of
an object.
For example,
class A
{
[...]
template <typename E, typename T>
friend std::basic_ostream< E, T>& operator<<( std::basic_ostream< E, T>&
os, const A& obj)
{
os << obj.x;
return os;
}
template
friend std::basic_istream< E, T>& operator>>( std::basic_istream< E, T>&
is, A& obj)
{
is >> obj.x;
return is;
}
private:
int x;
};
You have in STL file streams, string streams and you can find other kind of
streams (for sockets for example).
the usage is very simple:
A obj1, obj2;
std::cout << obj1 << obj2;
Catalin
P.S. The code is just a sketch. It may not compile.
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Rolf Magnus
Guest
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| Posted: Thu Oct 28, 2004 10:33 am Post subject: Re: objectStream in C++? |
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Jens wrote:
| Quote: | Hi
Is there at class in C++ to make objectstreams or shall I make it
yourself?
|
That depends on what an "objectstream" is.
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Jens
Guest
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| Posted: Thu Oct 28, 2004 11:27 am Post subject: Re: objectStream in C++? |
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Catalin Pitis wrote:
| Quote: |
"Jens" <jens.cortsenremovethiis (AT) tiscali (DOT) dk> wrote in message
news:4180be42$0$93475$eprecisef (AT) dread15 (DOT) news.tele.dk...
Hi
Is there at class in C++ to make objectstreams or shall I make it
yourself?
Thanks
Jens
A common solution is to define streaming operators for stream in and out
of an object.
For example,
class A
{
[...]
template <typename E, typename T
friend std::basic_ostream< E, T>& operator<<( std::basic_ostream< E,
T>&
os, const A& obj)
{
os << obj.x;
return os;
}
template
friend std::basic_istream< E, T>& operator>>( std::basic_istream< E,
T>&
is, A& obj)
{
is >> obj.x;
return is;
}
private:
int x;
};
You have in STL file streams, string streams and you can find other kind
of streams (for sockets for example).
the usage is very simple:
A obj1, obj2;
std::cout << obj1 << obj2;
Catalin
P.S. The code is just a sketch. It may not compile.
Hi |
My problem is to write a vector
into a vector<float>. Sorry I not where precise.
Jens
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Catalin Pitis
Guest
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| Posted: Thu Oct 28, 2004 11:35 am Post subject: Re: objectStream in C++? |
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"Jens" <jens.cortsenremovethiis (AT) tiscali (DOT) dk> wrote
| Quote: | Catalin Pitis wrote:
"Jens" <jens.cortsenremovethiis (AT) tiscali (DOT) dk> wrote in message
news:4180be42$0$93475$eprecisef (AT) dread15 (DOT) news.tele.dk...
Hi
Is there at class in C++ to make objectstreams or shall I make it
yourself?
Thanks
Jens
A common solution is to define streaming operators for stream in and out
of an object.
For example,
class A
{
[...]
template <typename E, typename T
friend std::basic_ostream< E, T>& operator<<( std::basic_ostream< E,
T>&
os, const A& obj)
{
os << obj.x;
return os;
}
template
friend std::basic_istream< E, T>& operator>>( std::basic_istream< E,
T>&
is, A& obj)
{
is >> obj.x;
return is;
}
private:
int x;
};
You have in STL file streams, string streams and you can find other kind
of streams (for sockets for example).
the usage is very simple:
A obj1, obj2;
std::cout << obj1 << obj2;
Catalin
P.S. The code is just a sketch. It may not compile.
Hi
My problem is to write a vector
into a vector<float>. Sorry I not where precise.
Jens
|
Here is some code
vector< float> vecToStore;
// ... initialize it
// Output to stream cout, with space delimiters
copy ( vecToStore.begin ( ), vecToStore.end ( ),
ostream_iterator<float> ( cout, " " ) );
vector< float> vecToLoad;
// Input from stream cin
copy( istream_iterator<float>( cin), istream_iterator<float>(),
vecToLoad.begin());
Again, it is just a sketch.
Catalin
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John Harrison
Guest
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| Posted: Thu Oct 28, 2004 12:20 pm Post subject: Re: objectStream in C++? |
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| Quote: |
Here is some code
vector< float> vecToStore;
// ... initialize it
// Output to stream cout, with space delimiters
copy ( vecToStore.begin ( ), vecToStore.end ( ),
ostream_iterator<float> ( cout, " " ) );
vector< float> vecToLoad;
// Input from stream cin
copy( istream_iterator<float>( cin), istream_iterator<float>(),
vecToLoad.begin());
|
Should be
copy( istream_iterator<float>( cin), istream_iterator<float>(),
back_inserter(vecToLoad));
Also the code above uses a text representation of the floating point
numbers, which is good because its portable. But if you want a binary
representation, try this
vector< float> vecToStore;
vector< float>::size_type size = vecToStore.size();
out.write((char*)&size, sizeof size);
if (size > 0)
out.write((char*)&vecToStore[0], size*sizeof(float));
vector< float> vecToLoad;
vector< float>::size_type size;
in.write((char*)&size, sizeof size);
if (size > 0)
{
vecToLoad.resize(size);
in.write((char*)&vecToLoad[0], size*sizeof(float));
}
Again untested.
john
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