Polimorphe Vector

[Marcelo]

Hello,

I would like to know if it is possible to implement in C the Vector class of
java. I would like to have and object (or something like) that makes this:

Let's call v the vector:

v[0] is a String
v[1] is an int
v[2] is an array.
....etc ...

I would like to know if there is another possibility than creating a struct.

In java, there is a vector implementation for this (with an iterator variable).
Besides, java permits to test the type of the object. Is it possible to do it in
C (having something like "instanceof") ??

thank you very much for your help,

Marcelo

 

[Richard Heathfield]

Marcelo said:

Hello,

I would like to know if it is possible to implement in C the Vector class
of java. I would like to have and object (or something like) that makes
this:

Let's call v the vector:

v[0] is a String
v[1] is an int
v[2] is an array.
...etc ...

I would like to know if there is another possibility than creating a
struct.

Yes, this is possible, but only using C constructs that you probably already
know about - arrays, pointers, etc. It's a LOT of work, but can be worth it
if you really, really need dynamic typing.

In java, there is a vector implementation for this (with an iterator
variable). Besides, java permits to test the type of the object. Is it
possible to do it in C (having something like "instanceof") ??

As I said, it *is* possible - but there is no C syntax that is explicitly
designed to support it.

 

[Zara]

Hello,

I would like to know if it is possible to implement in C the Vector class of
java. I would like to have and object (or something like) that makes this:

Let's call v the vector:

v[0] is a String
v[1] is an int
v[2] is an array.
...etc ...

I would like to know if there is another possibility than creating a struct.

In java, there is a vector implementation for this (with an iterator variable).
Besides, java permits to test the type of the object. Is it possible to do it in
C (having something like "instanceof") ??

thank you very much for your help,

Marcelo

Try using std::vector<boost:variant> or std::vector<boost::any>

www.boost.org

It is not STD C++, but it might be in a near future

Best regards,

-- Zara

 

[Ingo Menger]

Hello,

I would like to know if it is possible to implement in C the Vector class of
java. I would like to have and object (or something like) that makes this:

Let's call v the vector:

v[0] is a String
v[1] is an int
v[2] is an array.
...etc ...

This is not the way the class Vector is to be used in Java. As of Java
1.5, the javadoc tells us the following:

public class Vector<E> extends AbstractList<E> implements List<E>

That means, that all elements of the vector should be of one and the
same type, symbolized by E.

If you want just a dynamic array then pointers, malloc(), realloc() and
free() are your friends.

Besides, java permits to test the type of the object. Is it possible to do it in
C (having something like "instanceof") ??

No.
But you can implement something like it with a union. For example:

enum Kind { String, Int, Whatever };

struct Data {
enum Kind kind;
union {
char *strval;
int intval;
...
} u;
};

 

[Chuck F.]

.... snip ...

Try using std::vector<boost:variant> or std::vector<boost::any>

www.boost.org

It is not STD C++, but it might be in a near future

This is c.l.c. The C++ language is off-topic here.