Determine if the argument is integer or string

[alexeyv]

I've encountered a following code to determine if the argument is an integer or a string:

Code: Select all

{' '≡↑0⍴⍵}

This works! But how else it is possible to detect it in pure APL-way ?

[Morten|Dyalog]

Strictly speaking, that expression tells you whether the argument is character or not, it doesn't tell you what kind of number (boolean, integer, float, complex) it might be. On the other hand, I would say that it is "pure APL", since it only uses primitives.

It might be more direct to use ⎕DR, which returns a number which is the data type + 10×the bit size of the element:

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      {(⍕¨⍵),⍪⎕DR¨⍵}'A' '⍋' (0 1) 127 1000 40000 1.1 1J2
 A        80
 ⍋       160
 0 1      11
 127      83
 1000    163
 40000   323
 1.1     645
 1J2    1289


Type 0 is character, 3 is integer (but boolean arrays can have type 1). You can read all about ⎕DR on the online help pages

[PGilbert]

In case this is helping:

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isString←{0 2∊⍨10|⎕DR ⍵}

[michaelk]

I use ischar←{(⎕DR ⍵)∊80 160 320}

[JohnS|Dyalog]

At present, numbers have an odd ⎕DR type, so this fork works:

      isnum ← 2|⎕DR

However, we might be forced to break this rule in future when allocating the remaining codes: 4, 6 and 8.

[alexeyv]

Thanks for all answers!

[norbertjurkiewicz84]

isChar←{0=80|⎕DR ⍵}