"Counter" (Data Structure)

"Counter"

represents a mutable integer counter.

Details

  • A mutable integer counter can be used to count elements in any part of a program:
  • CreateDataStructure[ "Counter",i]create a new "Counter" with specified initial value i
    Typed[x,"Counter"]give x the type "Counter"
  • For a data structure of type "Counter", the following operations can be used:
  • ds["Copy"]return a copy of dstime: O(1)
    ds["Decrement"]decrement the counter, returning the old valuetime: O(1)
    ds["Get"]get the value of the counter stored in dstime: O(1)
    ds["Increment"]increment the counter, returning the old valuetime: O(1)
    ds["PreDecrement"]decrement the counter, returning the new valuetime: O(1)
    ds["PreIncrement"]increment the counter, returning the new valuetime: O(1)
    ds["Set",i]set the counter stored in ds to be itime: O(1)
    ds["Visualization"]return a visualization of dstime: O(1)
  • The following functions are also supported:
  • dsi===dsjTrue, 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

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Basic Examples  (1)

A new "Counter" can be created with CreateDataStructure:

Extract the value stored:

Increment the value stored in the counter:

Confirm that the value has updated:

Return an expression version of ds:

A visualization of the data structure can be generated:

Scope  (2)

Mutability  (1)

Create a new "Counter" data structure and initialize it:

Define a function that increments the counter if its argument is even:

Scan the function over all elements of an expression:

The number of even elements in the expression:

Information  (1)

A new "Counter" can be created with CreateDataStructure:

Information about the data structure ds:

Properties & Relations  (1)

Create a new "Counter" data structure and initialize it:

Incrementing the counter returns the old counter value:

Pre-incrementing the counter returns the current counter value:

Setting the counter returns the current counter value:

Possible Issues  (1)

The "Counter" data structure may only be initialized with a 64-bit integer:

Introduced in 2020
 (12.1)