What ⍬ means
It is a list with zero items. APL is a programming language designed to work with arrays—collections of values. A vector is a one-dimensional array, like a list. The number 0 is one value; ⍬ contains no values at all. For example, X←⍬ sets the variable X to an empty numeric vector.
APL can also construct an empty numeric vector with ⍳0 or 0⍴0; ⍬ writes that value directly. These alternative expressions remain useful for understanding existing code.
You may also meet ⍬⍴A. Here reshapes an array, and ⍬ specifies no dimensions: the result is a scalar, a single item rather than a list. For a nonempty A, it uses A's first item.
Part of the collection
Don't confuse it with
3
Questions people ask
1Is ⍬ the same as an empty string?
No. '' is an empty character vector, used for text; ⍬ is numeric. Both can display without visible contents, but their types differ.
More like this
10
How to type or find ⍬
- Also called
- zero tilde
- Search it as
- APL empty vector · empty numeric vector
- Shows up in
- Anything that takes text · its shape is whatever your font draws
⍬\236CCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.