Hey guys, was wondering if someone could help me better understand Unions. . . . haven't used them a lot, but I want to try them out. There aren't any tutorials though!

A Union is a kind of struct, but in memory its variables are not positioned besides each other but they 'share' the same memory. So if you have a undion like

union test_un {
int i;
char teststring[8];
};

you get a 8 byte union. The integer lies at the start of teststring. You can use that for example when you first need an integer and afterwards a string, like a variable which you can assign two different data types to.

I haven't used them yet, so this explanation might be not the best [addsig]

thx for that.. can anyone supply some practical uses for it?

This is the latest structure I have been using. . . it impliments a Union:

struct Node {
char * name;
char nodeType;
struct Node * next;
union {
struct {
long size;
} file;
struct {
struct Node * contents;
struct Node * parent;
} dir;
} nodeData;
};

Then you only have 1 structure, for 2 possible cases, a directory(dir) or a file.

-->-->you get a 8 byte union

since a char by itself is 8 bytes, you'd actually get an 64(8*8) byte union [addsig]

-->-->you get a 8 byte union

since a char by itself is 8 bytes, you'd actually get an 64(8*8) byte union
_________________
-Ken



I think I know who's going to be Coder Of the Month this time...

-KEN-, I really have to say you surprise me...Never have I heard greater bullshit. Maybe a char is 8 [b]bit[/] but never ever in life it's 8 byte sized.

Ain't that the proof that windows users loose the sight for the internals? [addsig]

That's a funny error, but I would not generalize because of that... If you take the _average_ windows user, perhaps, but this is the ypn..

I know that Peter, but -KEN- provoked the Linux community so many times that I just wanted to use this opportunity to kick back a little

Don't take it too serious -KEN-! [addsig]

It was a joke, but ok...

I wanted to find a rolleyes smiley to add to that post, but this board doesn't have a little smiley selection panel, so it was kinda hard to denote the joke...

Oh well... [addsig]

-->--> It was a joke, but ok...

No, I don't think so...

-->--> I wanted to find a rolleyes smiley to add -->--> to that post, but this board doesn't have -->--> a little smiley selection panel, so it
-->--> was kinda hard to denote the joke...

How about opening the FAQ in another window and taking the right smiley code frome there???

So, making a dumb mistake is one thing, and it happens to the best, so forget it. But saying it was a joke afterwards...I don't know...
[addsig]

-->-->[some rambling on FAQs]

Considering I barely frequent these boards, ask me if I knew this



And it really was a joke...But then again, like I really care what you think? [addsig]

A union is a user-defined data type that can hold values of different types at different times. It is similar to a structure except that all of its members start at the same location in memory. A union variable can contain only one of its members at a time. The size of the union is at least the size of the largest member.