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Reference · stzList

FindNthPrevious()

FindNthPrevious(n, pItem, pnStartingAt): word-order alias over FindPreviousNthOccurrence -- find the Nth occurrence of pItem walking backwards from pnStartingAt. Accepts :StartingAt = n.

Basic examples (2)

Softanza
o1 = new stzList([ 1, 2, 3, "A":"C", 5, 7, 8, 9, "A":"C" ])
? o1.FindNthPrevious(2, "A":"C", :StartingAt = 7)
Output
0

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 289_findnthprevious.ring(opens in a new tab)

Softanza
o1 = new stzList([ 1, 2, 3, "A":"C", "A":"C", 6, 7, "A":"C" ])
? o1.FindNthPrevious(2, "A":"C", :StartingAt = 7)
Output
4

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 290_findnthprevious.ring(opens in a new tab)

Scope (3)

Softanza
o1 = new stzList([ "1", "2", "♥", "4", "♥", "6", "7" ])
? o1.FindPrevious("♥", :StartingAt = 5)
? o1.FindNthPrevious(2, "♥", :StartingAt = 6)
Output
3
3

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 276_findprevious.ring(opens in a new tab)

Softanza
o1 = new stzList([ "_", "_", "♥", "_", "_", "♥", "_" , "♥", "_", "_" ])
? o1.FindPrevious("♥", :StartingAt = 5)
? o1.FindNthPrevious(2, "♥", :StartingAt = 7)
? o1.FindNthPrevious(3, "♥", :StartingAt = 9)
Output
3
3
3

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 268_findprevious.ring(opens in a new tab)

Softanza
o1 = new stzList([ "_", "_", "♥", "_", "_", "♥", "_" ])
? o1.FindFirst("♥")
? o1.FindLast("♥")
? o1.FindNext("♥", :StartingAt = 3)
? o1.FindPrevious("♥", :StartingAt = 6)
? o1.FindNthNext(1, "♥", :StartingAt = 6)
? o1.FindNthNext(1, "♥", :StartingAt = 5)
? o1.FindNthPrevious(2, "♥", :StartingAt = 7)
Output
3
6
6
3
0
6
3

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 282_findfirst.ring(opens in a new tab)

The extensions of this method

Each extension, and whether it exists for this method; an extension that exists combines with the others (FindSTCS).

Extension
Exists
What it adds · The names
Q
no
does what the method does, then returns the object, so the call can be chained
QQ
no
chains on the next, more specific type of object (the Q ladder)
QQQ
no
chains on the most specific type of object (the Q ladder)
QRT
no
returns the result as an object of the requested type
CS
yes
takes a case-sensitivity flag · FindNthPreviousCS
ST
no
takes the position to start from (StartingAt)
IB
no
takes bounds that are included (IncludingBounds)
XT
no
the extended form: more parameters than the base method
XTT
no
yet another extension: a further extended form, after XT
Z
no
includes the position in what it returns
ZZ
no
returns positions as sections, [start, end]
W
no
selects by a condition
WF
no
selects by a condition, with the expressive keywords (@NextItem, @PreviousItem...)
D
no
takes a direction, forward or backward (Directional)
F
no
takes a function (the condition or the update is given as a function); the forms document also uses F for the future form, which defers the action
Many
no
works on a collection of items instead of one (the plural form)
Except
no
takes exceptions, what to leave out (the exceptional form)
U
no
returns the result without duplication

Every example is a test file of the library, run inside the library for this page; only those whose output kept every promise their file wrote are shown.

See also