FindPrevious()

FindPrevious(pcSub, nFrom): mirror of NextOccurrence -- highest position strictly before nFrom.

Basic examples (2)

Softanza

o1 = new stzString("[••[•[••]•[•]]••[••]]")
? o1.FindNext("[", :StartingAt = 17)
? o1.FindPrevious("]", :StartingAt = 13)

Output

0
9

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 307_findnext.ring(opens in a new tab)

Softanza

o1 = new stzString("12♥4♥67")
# previous from 5
? o1.FindPrevious("♥", :StartingAt = 5)
# 2nd previous from 6
? o1.FindNthPrevious(2, "♥", :StartingAt = 6)

Output

3
3

run on 2026-10-02 04:24 inside the library at commit 0e72e2e2c; taken from 988_findprevious.ring(opens in a new tab)

Scope (4)

Softanza

o1 = new stzString("12♥♥♥67♥♥♥12♥♥♥")
# the 1st from position 3 is 3 itself
? o1.FindNthST(1, "♥♥♥", :StartingAt = 3)
# the next after 3
? o1.FindNext("♥♥♥", :StartingAt = 3)
# the previous before 10 must END before 10
? o1.FindPrevious("♥♥♥", :StartingAt = 10)

Output

3
8
3

run on 2026-10-02 04:24 inside the library at commit 0e72e2e2c; taken from 316_findnthst.ring(opens in a new tab)

Softanza

o1 = new stzString("..•.•..")
? o1.FindNext("•", :StartingAt = 3)
? o1.FindNextNth(2, "•", :StartingAt = 2)
? o1.FindNextNth(2, "•", :StartingAt = 3)
? o1.FindPrevious("•", :StartingAt = 5)
? o1.FindPreviousNth(2, "•", :StartingAt = 7)
? o1.FindPreviousNth(1, "•", :StartingAt = 5)
? o1.FindPreviousNth(2, "•", :StartingAt = 5)

Output

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 304_findnext.ring(opens in a new tab)

Softanza

o1 = new stzString("12•4•67")
# next after 3
? o1.FindNext("•", :StartingAt = 3)
# no 2nd next after 3
? o1.FindNextNth(2, "•", :StartingAt = 3)
# previous before 5
? o1.FindPrevious("•", :StartingAt = 5)
# no 2nd previous before 5
? o1.FindPreviousNth(2, "•", :StartingAt = 5)

Output

run on 2026-10-02 04:24 inside the library at commit 0e72e2e2c; taken from 989_findnext.ring(opens in a new tab)

Softanza

o1 = new stzString("•••••••••")
# FindNext('') is 0
? o1.FindNext("", :StartingAt = 1)
# FindNext('x') (absent) is 0
? o1.FindNext("x", :StartingAt = 1)
# FindNext('•', from 5) is 6
? o1.FindNext("•", :StartingAt = 5)
# FindNthNext(6, '•', from 3) is 9
? o1.FindNthNext(6, "•", :StartingAt = 3)
# FindNthNext(5, '•', from 1) is 6
? o1.FindNthNext(5, "•", :StartingAt = 1)
# FindPrevious('•', from 5) is 4
? o1.FindPrevious("•", :StartingAt = 5)
# FindPrevious('•', from 2) is 1
? o1.FindPrevious("•", :StartingAt = 2)
# FindNthPrevious(8, '•', from 9) is 1
? o1.FindNthPrevious(8, "•", :StartingAt = 9)
# FindNthPrevious(3, '•', from 4) is 1
? o1.FindNthPrevious(3, "•", :StartingAt = 4)

Output

run on 2026-10-02 04:23 inside the library at commit 0e72e2e2c; taken from 236_findnext.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

does what the method does, then returns the object, so the call can be chained

chains on the next, more specific type of object (the Q ladder)

QQQ

chains on the most specific type of object (the Q ladder)

QRT

returns the result as an object of the requested type

takes a case-sensitivity flag

takes the position to start from (StartingAt)

takes bounds that are included (IncludingBounds)

the extended form: more parameters than the base method

XTT

yet another extension: a further extended form, after XT

includes the position in what it returns

returns positions as sections, [start, end]

selects by a condition

selects by a condition, with the expressive keywords (@NextItem, @PreviousItem...)

takes a direction, forward or backward (Directional)

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

works on a collection of items instead of one (the plural form)

Except

takes exceptions, what to leave out (the exceptional form)

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.

FindPrevious()

Basic examples (2)

Scope (4)

The extensions of this method

See also