How to set value of queue to another queue?

Question

How can I enqueue value of a queue (not it reference) to another queue? It work like I have a queue of points in C++ (Queue<*word>), but I want to copy value of buffer queue like this

a = 1;
int[] array = new int[1]
array[0] = a //array[0] now is 1
a = 0 // but array[0] doesn't change, array[0] is 1!

I have problem in words.Enqueue(buffer)

using word = System.Collections.Generic.Queue<char>;

Queue<word> words = new Queue<word>();  //word is the custom type, that was def in file top
word buffer = new word();

for (var symbol_count = 0; symbol_count < text.Length; ++symbol_count)
{

    if (text[symbol_count] != ' ' && text[symbol_count] != '.' && text[symbol_count] != ',')
    {
        buffer.Enqueue(text[symbol_count]); //store one char in word
    } 
    else 
    {
        buffer.Enqueue(text[symbol_count]); //store end of word symbol
        words.Enqueue(buffer);  //store one word in words queue, but compiler do it like I try to copy a reference of buffer, not it value!!!
        //System.Console.WriteLine(words.Count); DEBUG
        buffer.Clear(); //clear buffer and when i do this, value in words queue is deleted too!!!
    }
}

*"I have problem in words.Enqueue(buffer)"*. So what is the problem? — Sach, Aug 01 '19 at 19:24
I insert in "words" queue not a value of "buffer" queue, but it's pointer. And when I change a value of "buffer" queue, it also change in "words" queue. But I want just copy a value of "buffer" queue in "words" queue — Magician Artemka, Aug 01 '19 at 19:26
Duplicate of https://stackoverflow.com/questions/16209747/cloning-queue-in-c-sharp. Or just create a new queue instead of `Clear`ing the old one. — Eugene Podskal, Aug 01 '19 at 19:34
@Rufus L, sorry for this, I thought that this trick improve readability of code :C — Magician Artemka, Aug 01 '19 at 19:34
I'm not sure if I understand your question fully, but it sounds like you want to make a deep copy of a value in your queue and enqueue it in a different queue? Here's a link that might help: https://stackoverflow.com/questions/129389/how-do-you-do-a-deep-copy-of-an-object-in-net-c-specifically — dustinos3, Aug 01 '19 at 19:35

score 3 · Accepted Answer · answered Aug 01 '19 at 19:40

The problem is that you're re-using the same buffer in your loop, so when you clear it, all the references to it are also cleared.

Instead, set the local buffer variable to a new instance of the object, so that any changes to it don't affect the reference we just stored:

foreach (char chr in text)
{
    buffer.Enqueue(chr);

    if (chr == ' ' || chr == '.' || chr == ',')
    {                     
        words.Enqueue(buffer);

        // reassign our local variable so we don't affect the others
        buffer = new Queue<char>();   
    }
}

Thank you for help! – Magician Artemka Aug 01 '19 at 19:45 — Magician Artemka, Aug 01 '19 at 19:45

score 1 · Answer 2 · answered Aug 01 '19 at 19:37

1

When you save a new word to a queue (you might have a bug with the last word here, by the way)

words.Enqueue(buffer);

You shouldn't use the buffer variable itself: it holds a reference to the temporary data and you need to make a copy of it first, something that will not be modified in the next lines.

Try e.g.

words.Enqueue(new word(buffer));

answered Aug 01 '19 at 19:37

DK.

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Thank you for help! – Magician Artemka Aug 01 '19 at 19:45
@MagicianArtemka you are welcome. Note though, that I was answering your question here, basically _how to use queue value and "detach" it from queue reference_. For the underlying problem, however, the code by Rufus is more straightforward and efficient. – DK. Aug 01 '19 at 20:23

How to set value of queue to another queue?

2 Answers2