Queue<T>

Struct · namespace System · Since 0.09

struct Queue<T>

A queue of values: first in, first out.

var jobs = Queue<string>.Create();
jobs.Enqueue("load");
jobs.Enqueue("draw");
string next = jobs.Dequeue();         // "load"
if (jobs.TryDequeue() is string s)    // no panic when the queue is empty
    ...

Like List<T>, a Queue is a small handle to shared storage: copies see the same elements. foreach and Get(i) go from the front (the next Dequeue) to the back. The elements are kept in a ring buffer, so Enqueue and Dequeue do not move the other elements.

Static methods

Name	Description
Create	A new, empty queue.

Create

static Queue<T> Create()

A new, empty queue.

static Queue<T> Create(int capacity)

A new, empty queue with room for capacity elements before it has to grow.

Methods

Name	Description
IsCreated	Whether the queue has storage: made by Create(), not the zero value (which cannot change).
Count	The number of elements.
Enqueue	Adds value at the back of the queue.
Dequeue	Removes and returns the front element.
TryDequeue	Removes and returns the front element, if there is one.
Peek	The front element, without removing it.
TryPeek	The front element without removing it, if there is one.
Get	The element index places behind the front (0 is the front).
Contains	Whether an element equals value (IEquatable).
Clear	Removes all elements.
ToArray	The elements from the front to the back (the order Dequeue would return them).

IsCreated

bool IsCreated()

Whether the queue has storage: made by Create(), not the zero value (which cannot change).

Since 0.26

Count

int Count()

The number of elements.

Enqueue

void Enqueue(T value)

Adds value at the back of the queue.

Panics when the queue was not created (Queue<T>.IsCreated).

Dequeue

T Dequeue()

Removes and returns the front element.

Panics when the queue is empty (Queue<T>.TryDequeue does not).

TryDequeue

Optional<T> TryDequeue()

Removes and returns the front element, if there is one.

Returns nothing (null) when the queue is empty.

Peek

T Peek()

The front element, without removing it.

Panics when the queue is empty (Queue<T>.TryPeek does not).

TryPeek

Optional<T> TryPeek()

The front element without removing it, if there is one.

Returns nothing (null) when the queue is empty.

Get

T Get(int index)

The element index places behind the front (0 is the front).

Panics when index is not in 0 to Count() - 1.

Contains

bool Contains(T value) where T : IEquatable<T>

Whether an element equals value (IEquatable).

Clear

void Clear()

Removes all elements.

ToArray

T[] ToArray()

The elements from the front to the back (the order Dequeue would return them).