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Allocating an array of objects ?
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Join Date: May 2008
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Hi,
assuming that Element is a class,I prefer to create an array of objects size of which is unknown in this way:
Is there another way to create an array of objects size of which is unknown without using new key(without malloc too)?
I am asking this question, because I have to create this array in a function.As you know, a variable created in a function scope is automatically destroyed at the end of the scope.
On the other hand,when we use new,we have to use delete.I think that using new-delete in a function scope is meaningless,if there is a way not to use them.
So,what are your suggestions?
assuming that Element is a class,I prefer to create an array of objects size of which is unknown in this way:
Element *elementArray = new Element[length]; Is there another way to create an array of objects size of which is unknown without using new key(without malloc too)?
I am asking this question, because I have to create this array in a function.As you know, a variable created in a function scope is automatically destroyed at the end of the scope.
On the other hand,when we use new,we have to use delete.I think that using new-delete in a function scope is meaningless,if there is a way not to use them.
So,what are your suggestions?
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Don't know if it helps. I myself am not sure if it's ok to write it, but compiler doesn't complain:
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Originally Posted by Sci@phy 
Don't know if it helps. I myself am not sure if it's ok to write it, but compiler doesn't complain:
C++ Syntax (Toggle Plain Text)
anyway, I learned the solution:local pointers should be handled before going out of scope.
Last edited by gangsta1903; Oct 24th, 2008 at 5:27 pm.
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Glad you've find answer. But this is what you asked (be careful what you ask ):
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Is there another way to create an array of objects size of which is unknown without using new key(without malloc too)?
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Originally Posted by Sci@phy
Don't know if it helps. I myself am not sure if it's ok to write it, but compiler doesn't complain:
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int a[n]; is not valid C++. Your compiler doesn't complain because it supports this as an extension. (Your compiler might also support the 1999 C standard (where such things are valid)).To answer the original question, though, it depends on what you mean by "not using new key (without malloc too)". If you mean that your code does not invoke operator new or call malloc() directly, then you can use a standard container (std::vector, std::list, etc).
However, those containers work by performing dynamic memory allocation behind the scenes ... which means that code you write may not employ operator new or malloc(), but the containers themselves might.
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Originally Posted by grumpier
The array declaration int a[n]; is not valid C++. Your compiler doesn't complain because it supports this as an extension. (Your compiler might also support the 1999 C standard (where such things are valid)). •
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In C# this would be easy.
Use jagged arrays!
But yeah if you're sticking to C++ you might want to read http://blog.voidnish.com/?p=16
Use jagged arrays!
But yeah if you're sticking to C++ you might want to read http://blog.voidnish.com/?p=16
Today is a gift, that's why it is called "The Present".
Make love, no war. Cave ab homine unius libri.
Danny
Make love, no war. Cave ab homine unius libri.
Danny
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Originally Posted by ddanbe
In C# this would be easy.
Use jagged arrays!
But yeah if you're sticking to C++ you might want to read http://blog.voidnish.com/?p=16
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