# "Queue"(Data Structure)

"Queue"

represents a queue of expressions.

# Details

• A queue is a collection of elements that supports first-in, first-out insertion and removal:
•  CreateDataStructure["Queue"] create a new empty "Queue" CreateDataStructure["Queue",elems] create a new "Queue" containing elems Typed[x,"Queue"] give x the type "Queue"
• For a data structure of type "Queue", the following operations can be used:
•  ds["Copy"] return a copy of ds time: O(n) ds["DropAll"] drop all the elements from ds time: O(n) ds["Elements"] return a list of the elements of ds time: O(n) ds["EmptyQ"] True, if ds is empty time: O(1) ds["Fold",fun,init] apply fun to the elements of ds, starting with init, accumulating a result time: O(n) ds["Length"] number of elements in ds time: O(1) ds["Peek"] first element in ds time: O(1) ds["Pop"] remove the first element of ds time: O(1) ds["Push",x] add x to the end of ds time: O(1) ds["PushList",elems] add elems to the end of ds time: O(nelems) ds["Visualization"] return a visualization of ds time: O(n)
• The following functions are also supported:
•  dsi===dsj True, if dsi equals dsj FullForm[ds] full form of ds Information[ds] information about ds InputForm[ds] input form of ds Normal[ds] convert ds to a normal expression

# Examples

open allclose all

## Basic Examples(2)

A new "Queue" can be created with CreateDataStructure:

ds is initially empty:

Add an element to the end of ds:

ds is no longer empty:

It has one element:

Add another element and peek. This shows the first element:

Remove the first element:

Return an expression version of ds:

It is fast to put elements into a queue:

A visualization of the data structure can be generated:

Sum all the elements:

## Scope(1)

### Information(1)

A new "Queue" can be created with CreateDataStructure:

Information about the data structure ds: