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Mar 26th, 2009

array of structs

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I have a struct. I want to declare a pointer to that struct. Now I want 10 of those structs. How is this declared? I have tried (call the struct foo for example):

foo* test[10];

when I make a call to test[0]->whatever or test[5]->whatever it seems to always write to the first element (the 0th of the array).

I think what I'm getting is an array of pointers. I want a pointer to an array of structs.

How do I delare this? Thanks.

Last edited by Nemoticchigga; Mar 26th, 2009 at 11:17 am.

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Nemoticchigga

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Mar 26th, 2009

Re: array of structs

Yes, you are getting an array of pointers.

Instead, declare your array of structs:
foo test[10];

Now you have 10 foo objects and foo[0].myMember will reference the contents of the first one.

To get a pointer you then use:
foo* pFoo = &test[0];
which will give you a pointer to the first one.

MrSpigot

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Mar 26th, 2009

Re: array of structs

Correction: you are getting an array of uninitialized pointers. Accessing them may result in undefined behaviour. So do it like MrSpigot recommends or use new to initialize the array members.

jencas

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Mar 26th, 2009

Re: array of structs

you can also do it like Jenca's second suggestion like:

c++ Syntax (Toggle Plain Text)
foo *test;
foo = new struct foo[10];
foo *test;
foo = new struct foo[10];

Last edited by SeeTheLite; Mar 26th, 2009 at 4:35 pm.

SeeTheLite

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Mar 26th, 2009

Re: array of structs

Thanks all.

MrSpigot, how would I then access the structs through the pointer?

pFoo->test[0].index = blah; does not work. How would this be done?

Thanks.

Nemoticchigga

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Mar 26th, 2009

Re: array of structs

Click to Expand / Collapse Quote originally posted by Nemoticchigga ...

Thanks all.

MrSpigot, how would I then access the structs through the pointer?

pFoo->test[0].index = blah; does not work. How would this be done?

Thanks.

pFoo->index = blah;
will access the first struct, but more generally you could use pFoo[n].index = blah;

Or modify pFoo:
pFoo += 1;
pFoo->index = blah; // pFoo now references the second struct

Last edited by MrSpigot; Mar 26th, 2009 at 6:18 pm.

MrSpigot

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